Leonard and Wolowitz clash over a work emergency; Amy throws a Victorian Christmas party which Sheldon resents.
Sheldon says goodbye to Fun With Flags; Howard, Leonard and Raj look through their dead professor's research; Bernadette learns her co-workers' true feelings.
Sheldon panics when Leonard announces he has to go into hospital for surgery, while Raj discovers his parents have divorced. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
The gang recreates a prom night on the roof of the apartment building when the girls decide they would like to re-enact their evenings with their current partners. However, Sheldon feels under pressure to take part in all the romantic traditions, and Howard worries about who Stuart will bring as his date. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Penny is left in a difficult professional situation when a doctor (guest star Billy Bob Thornton) turns up at her door following her flirtatious sales technique, so the guys try to help her out. Meanwhile, Amy and Bernadette have a dispute over whether female scientists should flaunt their sexuality to try to get ahead at work. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Leonard and Penny ask Howard and Bernadette for advice when they argue about money. Meanwhile, Sheldon and Raj try to find out whether they could survive a dark matter research expedition in a salt mine by attempting to simulate the conditions in a steam tunnel beneath the university. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Penny is forced to revise for a work assessment during the girls' trip to Las Vegas, and Amy and Bernadette accuse her of spoiling their fun. Meanwhile, the guys try to invent something of scientific importance - but only come up with new ways to procrastinate. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Raj's girlfriend Emily (Laura Spencer) gives Penny the cold shoulder when she learns about his past. Meanwhile, the guys debate investing in Stuart's comic-book shop and becoming part owners of the business. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Tomorrow at 8:00pm EST - WCBS (CBS)
Leonard and Penny attempt to prove Sheldon wrong when he claims that he and Amy have a superior relationship. Meanwhile, Howard is nervous when Nasa asks him to throw the first pitch at a baseball game honouring National Space Day. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Sheldon is forced to teach a course at the university, and Howard surprises the gang when he decides to enrol on it. Meanwhile, Amy plays Penny and Bernadette off against each other while the tension brews over Penny's new job. Comedy, guest starring Regina King, with Johnny Galecki, Jim Parsons and Kaley Cuoco
The comedy returns as Leonard and Amy are forced to take an unexpected road trip to Arizona to pick up Sheldon after his epic railway journey ends in chaos. Meanwhile, Howard finds Stuart's relationship with his mother strange, and Penny has an interview for a sales job at Bernadette's work place. Starring Johnny Galecki, Jim Parsons and Kaley Cuoco
In the seventh series finale, Sheldon becomes upset about his career, the destruction of the comic-book store and Leonard and Penny's future living arrangements. Elsewhere, Howard is unable to keep hold of a carer for his mother. Comedy, staring Johnny Galecki, Jim Parsons and Kaley Cuoco
Wednesday 31st December 10:00pm EST - Turner Broadcasting System
Penny gets fired from the movie, prompting her to takes a serious look at her life. Elsewhere, Raj gets advice from Sheldon after he sees Emily on a date with another man at the cinema, while Howard's mother breaks her leg. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Wednesday 31st December 9:30pm EST - Turner Broadcasting System
The gang's preparations for Star Wars Day are interrupted by the news that Professor Proton has died. Leonard and Penny attend the funeral, where they talk about their rejected marriage proposals, but Sheldon has difficulty dealing with the death of his childhood hero - until a surprise visitor helps him cope with his grief. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco, with a guest appearance by Bob Newhart
Wednesday 31st December 9:00pm EST - Turner Broadcasting System
Penny and Leonard try to distract Sheldon from his career woes by reinstating Anything Can Happen Thursday, but it causes friction among the gang when Amy and Bernadette are caught lying. Meanwhile, Raj seeks Howard's help in preparing for a date with Emily. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Wednesday 31st December 8:30pm EST - Turner Broadcasting System
Penny tries to help Sheldon when he starts to wonder whether he is wasting his time studying string theory. Meanwhile, during a dinner, Raj discovers Howard once embarrassed himself on a date with Emily. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Tuesday 30th December 10:30pm EST - Turner Broadcasting System
Raj is racked with guilt when he tries to date Lucy and Emily at the same time, Penny has trouble deciding whether to take a role in a film, and Sheldon struggles to choose between two gaming systems. Comedy, starring Kunal Nayyar, Jim Parsons and Kale Cuoco-Sweeting
Tuesday 30th December 9:30pm EST - Turner Broadcasting System
Sheldon is forced to confront a new reality when he visits his mother in Houston, while Raj's murder mystery party causes conflict for the rest of the gang members. Comedy, starring. Johnny Galecki, Jim Parsons and Kaley Cuoco
Tuesday 30th December 9:00pm EST - Turner Broadcasting System
After arguing with Sheldon, Howard tries to make amends by taking him to Nasa's headquarters in Houston. Elsewhere, Penny has second thoughts about quitting her job as a waitress when her car dies, while Amy tries to find Raj a date. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Tuesday 30th December 8:30pm EST - Turner Broadcasting System
Leonard's purchase of a dining-room table causes Sheldon to re-evaluate his life. Meanwhile, Howard is offered the chance to go back to the International Space Station, and Bernadette struggles to decide whether to encourage him. Comedy, starring Johnny Galecki, Jim Parsons and Melissa Rauch
Tuesday 30th December 8:00pm EST - Turner Broadcasting System
Sheldon and Amy take a train ride to Napa Valley with Howard and Bernadette on Valentine's Day. Comedy about four friends who understand more about the laws of physics than they do about interacting with other people, including a free-spirited woman called Penny. Johnny Galecki, Jim Parsons and Kaley Cuoco star
Thursday 1st January 8:00pm EST - WCBS (CBS)
When the guys are unable to get tickets for the Comic-Con, Leonard, Howard and Raj decide to buy fake passes from a stranger - but they then worry about getting caught with them. Sheldon decides to hold his own comic-book convention and searches for a suitable star guest for the event. Meanwhile, the girls take tea at a hotel but discover that maturity is over-rated. Comedy, guest starring James Earl Jones and Carrie Fisher
Monday 29th December 10:30pm EST - Turner Broadcasting System
Sheldon tries to relax after he is forced to take a vacation, while Penny quits her job, and Leonard struggles to be supportive of her. Elsewhere, Bernadette seeks Stuart's help in replacing one of Howard's comic books. Comedy about four friends who understand more about the laws of physics than they do about interacting with other people, including a free-spirited woman called Penny. Johnny Galecki, Jim Parsons and Kaley Cuoco star
Monday 29th December 10:00pm EST - Turner Broadcasting System
Penny makes an important decision after Leonard tries to help her in the aftermath of a failed role on a TV show. Comedy about four friends who understand more about the laws of physics than they do about interacting with other people, including a free-spirited woman called Penny. Starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Saturday 27th December 10:30pm EST - Turner Broadcasting System
While Sheldon is at home in Texas, the rest of the gang decorate for Christmas and reflect on how much he has changed their lives. Comedy about four friends who understand more about the laws of physics than they do about interacting with other people, including a free-spirited woman called Penny. Johnny Galecki, Jim Parsons and Kaley Cuoco star
Thursday 25th December 8:00pm EST - WCBS (CBS)
Sheldon is bothered by the attention he receives in the wake of his heavy element discovery, but is taken aback when his work is disproved by Leonard. Meanwhile, Raj makes Howard and Bernadette feel inadequate when he stays with them for a week and is the perfect house guest
Saturday 27th December 10:00pm EST - Turner Broadcasting System
Sheldon is dismayed when the group spends the Thanksgiving holiday at Mrs Wolowitz's house, but hits it off with Bernadette's father. Meanwhile, Penny realises she must deal with a mistake from her past when she and Leonard have an argument. Comedy, starring Jim Parsons and Kaley Cuoco
Leonard attempts to stop Sheldon from overreacting to a mistake, forcing Sheldon to make Leonard experience first hand what it's like to be him. Comedy about four friends who understand more about the laws of physics than they do about interacting with other people, including a free-spirited woman called Penny. Johnny Galecki, Jim Parsons and Kaley Cuoco star
Saturday 27th December 9:30pm EST - Turner Broadcasting System
Sheldon is hurt when Professor Proton (Bob Newhart) contacts Leonard for help, so he befriends TV scientist Bill Nye, and Raj gets jealous when Howard crashes a girls' night in making home-made jewellery. Starring Jim Parsons, Johnny Galecki, and Kunal Nayyar
Saturday 27th December 9:00pm EST - Turner Broadcasting System
Sheldon stumbles upon a major scientific breakthrough, causing him to feel like a fraud, while Penny steps up her game with Leonard after seeing Howard make a romantic gesture to Bernardette. Comedy, starring Jim Parsons, Johnny Galecki and Kaley Cuoco
Sheldon re-evaluates the time he spends with Amy when she takes a job at the university. Meanwhile, Howard is forced to sleep on his friend's sofa after he gets into an argument with Bernadette. Comedy, starring Jim Parsons, Simon Helberg and Mayim Bialik
Saturday 27th December 8:30pm EST - Turner Broadcasting System
Sheldon introduces Amy to Raiders of the Lost Ark - one of his favourite films - and is distraught when she ends up pointing out a plot hole that ruins the whole story. Meanwhile, Leonard realises he can manipulate Penny into feeling sorry for him when his mother publishes a reveal-all book about his childhood problems. Comedy, starring Jim Parsons and Johnny Galecki
Saturday 27th December 8:00pm EST - Turner Broadcasting System
The friends compete in a scavenger hunt designed by Raj to test their scientific knowledge and life skills, but the game brings out the best and worst in everyone. As the hunt progresses, Howard and Amy begin to bond over their shared musical tastes, while Penny and Sheldon work together as a team and Bernadette becomes fiercely competitive
Friday 26th December 9:30pm EST - Turner Broadcasting System
Leonard returns from his research expedition in the North Sea early and undergoes an adjustment period with Sheldon. Howard experiences an unusual emotional reaction as a result of his relationship with his mother. Johnny Galecki, Jim Parsons and Simon Helberg star
Friday 26th December 9:00pm EST - Turner Broadcasting System
Sheldon and Penny bond as they miss Leonard, and Howard tries to help Raj get over his break-up with Lucy. Meanwhile, Bernadette and Amy visit an out-of-town conference where they are hit on at a hotel bar. Comedy about four high-achieving scientists, starring Jim Parsons, Kaley Cuoco and Johnny Galecki
Friday 26th December 8:30pm EST - Turner Broadcasting System
Leonard is offered an exciting job opportunity, but it will mean he has to leave the country for several months. Penny tries to support his ambitions, while Sheldon is jealous and attempts to discourage him from accepting the post. Meanwhile, Raj pushes the boundaries with Lucy, but puts their relationship in jeopardy
Friday 26th December 8:00pm EST - Turner Broadcasting System
The guys invite the girls to a Dungeons & Dragons night when their trip to Vegas falls through after an incident with airport security. However, following a few drinks, Sheldon and Amy's relationship takes an unexpected turn. Meanwhile, Raj goes on a date with Lucy, who tries to sneak out of the restaurant's bathroom window - but ends up getting stuck and calling for his help
Thursday 25th December 10:30pm EST - Turner Broadcasting System
Leonard and Sheldon discover their favourite childhood TV science show host Professor Proton can be booked for private parties and decide to hire him to entertain them. Meanwhile, Raj asks Howard and Bernadette to look after his dog for the weekend, but the couple panic when the canine goes missing. Guest starring Bob Newhart
Thursday 25th December 10:00pm EST - Turner Broadcasting System
Amy tries to help Sheldon get over his desire for closure when one of his favourite TV shows is cancelled on a cliffhanger ending. Meanwhile, Raj discovers his new girlfriend Lucy has a blog in which she has written about him, but he is upset when he learns she believes he has feminine qualities, causing him to worry about their relationship
Thursday 25th December 9:30pm EST - Turner Broadcasting System
The guys compete for a tenured professor position at the university, leading them to try to win over the committee in charge of appointing a new staff member, and arguing about who deserves the spot the most. However, the panel includes Mrs Davis from Human Resources, whom Sheldon has crossed paths with before. Guest starring Regina King
Thursday 25th December 9:00pm EST - Turner Broadcasting System
Bernadette and Howard host a dinner party, but as it falls on Sheldon's Thai food night, he opts to bring his own dinner. As punishment for his lack of manners, the gang decides he should organise Wolowitz's cluttered wardrobe, but he discovers an unopened letter from Howard's father, who hasn't made contact in years
Tuesday 23rd December 10:30pm EST - Turner Broadcasting System
While the girls go to Disneyland and get made up as princesses, the guys have to promote science as a career option for women at Howard's old middle school. Meanwhile, Raj and Lucy have their first date in a library, where instead of speaking to each other they send text messages
Tuesday 23rd December 9:30pm EST - Turner Broadcasting System
Raj is upset when Lucy runs away in the middle of their date, leaving the gang to cheer him up. However, when Howard bumps into her she admits how shy she actually is and rearranges another outing with Raj. Meanwhile, Sheldon asks Penny to help with a new episode of Fun with Flags, and because he is impressed by her acting ability, the friends go to see her in a performance of A Streetcar Named Desire
Tuesday 23rd December 9:00pm EST - Turner Broadcasting System
Leonard and Penny celebrate Valentine's Day, but their evening takes a turn for the worse when the latter's ex-boyfriend proposes to his girlfriend in the same restaurant. Meanwhile, Sheldon enlists the help of his assistant Alex to find the perfect gift for Amy
Tuesday 23rd December 8:30pm EST - Turner Broadcasting System
Leonard moves in with Penny while he is mad at Sheldon. However, this leads Amy to suggest she would be the perfect roommate for Dr Cooper as she knows him so well and he wouldn't have to train anyone else. Meanwhile, Howard goes on a trip to Las Vegas with Bernadette and asks Raj to keep an eye on his mother while he is away
Tuesday 23rd December 8:00pm EST - Turner Broadcasting System
Sheldon is furious when the university forces him to work with Kripke, while Howard's hobby lands him in financial trouble. However, that doesn't stop him and Raj getting expensive action figures of themselves made - much to Bernadette's disapproval
Tomorrow at 10:30pm EST - Turner Broadcasting System
The guys become stranded in the middle of nowhere when Leonard's car is stolen en route to the Bakersfield comic-book convention. Meanwhile, back at home, the women try to work out why the guys are so fascinated with comic books
Tomorrow at 10:00pm EST - Turner Broadcasting System
Leonard is surprised when he realises Alex is attracted to him - but Sheldon is annoyed that his new assistant is not focusing on her work and attempts to get advice from the girls about what to do. However, the situation upsets Penny. Comedy, starring Johnny Galecki and Jim Parsons
Leonard tries to get Sheldon into the Christmas mood by playing a game, but things do not go as planned when Sheldon reveals a childhood trauma. Raj goes out with the girls and reveals he had crushes on both Penny and Bernadette - but not Amy. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Wednesday 24th December 11:00pm EST - WNYW (FOX)
As part of the relationship agreement, Sheldon reluctantly has to take care of Amy when she gets sick, but she loves the extra attention so much she pretends to remain in poor health. Elsewhere, Howard tries to get some tips on fishing from Penny when he and Bernadette go to visit her manly father
Sheldon feels undermined when his parking space at the university is allocated to Howard instead, and his determination to cling on to the spot causes a rift in the pair's friendship. However, the battle between the boys pales in comparison to that waged by Amy and Bernadette, whose disagreement on behalf of their significant others becomes increasingly personal. Comedy, starring Jim Parsons and Simon Helberg
The friends try to solve the mystery of Sheldon's post-lunch activities, following him to a secret room where they discover how he chills out. Elsewhere, Leonard is jealous when Penny starts texting a classmate, but things quickly change when Alex gets flirty with him
When Amy and Wil Wheaton get into a fight while filming Fun with Flags, Sheldon pays the consequences of their fall out. He ends up going to Penny for advice and gets drunk, prompting him to confront the actor in a bid to make him apologise. Bernadette encourages Howard to move out of his mother's house
Sheldon upsets guest star Stephen Hawking when they play an online game of Words with Friends, until Howard advises him to let the scientist win. Elsewhere, Penny enrols in a college class, but decides to keep it a secret from Leonard. Comedy, starring Jim Parsons and Simon Helberg
Stuart and Raj host a Halloween party at the comic-book store, and Howard talks incessantly about his work on board the International Space Station, annoying his wife and friends. Penny and Sheldon have a steamy encounter at the lab. Comedy, guest starring Buzz Aldrin, with Johnny Galecki, Jim Parsons and Kaley Cuoco
Thursday 1st January 11:00pm EST - WNYW (FOX)
Howard returns from his space mission, but the welcome from his friends and family does not meet his expectations. His night alone with Bernadette goes badly, his mother ignores him, and he realises Stuart has taken his place as Koothrappali's best friend. On top of that, Sheldon, Amy, Leonard and Penny kick him out of their group game night. Comedy, starring Simon Helberg
Thursday 1st January 12:30am EST - WNYW (FOX)
Sheldon hires an attractive female assistant, but when she becomes interested in Leonard, Penny decides to mark her territory by sleeping with him. Meanwhile, Howard starts to lose his mind when his return from space is delayed another week. Comedy, starring Jim Parsons
Tuesday 30th December 11:00pm EST - WNYW (FOX)
Penny tells the girls she is unsure about her relationship with Leonard and is considering breaking up with him, but when Sheldon finds out, he tries his best to change her mind. Meanwhile, on the International Space Station, Howard is being bullied by the other astronauts. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Monday 29th December 11:00pm EST - WNYW (FOX)
Despite being on the International Space Station, Howard gets caught in a strange argument between Bernadette and his mother via video link. Elsewhere, Raj feels lonely while his best friend is away and ends up interfering with Sheldon's and Leonard's dates. Comedy, starring Simon Helberg
Friday 26th December 11:00pm EST - WNYW (FOX)
As Howard and his fellow astronauts sit in the space shuttle awaiting launch, he reflects on the tumultuous events of the previous few days, when he and Bernadette tried to get married before he went into space. Meanwhile, his friends witness the blast-off on TV at home
Tuesday 23rd December 11:00pm EST - WNYW (FOX)
Howard tries to use his wedding as an excuse to avoid being sent into space but ends up accepting the mission. Amy plots to get Sheldon to take the next step in their relationship, while Leonard accidentally asks Penny to marry him after she agrees to sleep with him again
Tomorrow at 11:00pm EST - WNYW (FOX)
Leonard, Sheldon and Raj organise a bachelor party for Howard, but stories about his sexual history are unwittingly revealed by Raj, and his friend has to persuade bride-to-be Bernadette not to call the wedding off. Comedy, starring Simon Helberg and Kunal Nayyar
Wolowitz is put in charge of looking after Stephen Hawking's wheelchair when the famous scientist comes to lecture at the university for a week. Sheldon is desperate to meet Hawking so Wolowitz takes advantage of his position of privilege to blackmail Sheldon into doing the most unpleasant tasks. Guest starring Stephen Hawking
Penny buys Leonard and Sheldon some Star Trek action figures, but the duo refuse to remove them from the packaging in case their value is diminished. Elsewhere, Raj is desperate to find someone to accompany him to a wedding and asks his parents to find him a date. Featuring the guest voice of Leonard Nimoy (Star Trek)
Amy is disappointed when Sheldon breaks his promise to go with her to her aunt's birthday party, and instead decides to join the boys for a Star Wars video game marathon lasting the entire weekend. Comedy, starring Mayim Bialik and Jim Parsons
Sheldon refuses to get his hair cut after his regular barber passes away - a solitary change that causes chaos in the rest of his well-ordered life. Meanwhile, Howard undergoes a gruelling Nasa training programme in Houston, Texas, meaning he can only communicate with Bernadette via the internet
Leonard, Raj and Howard devise a contest to decide whether Sheldon or Kripke should get Professor Rothman's vacant corner office. Meanwhile, Penny receives the gift of a painting from Amy to celebrate their friendship, but discreetly tries to dispose of it with help from Bernadette
Sheldon uses his holidays to help Amy in her biology lab, and is soon moaning about the menial jobs he is given, until she asks him to dissect a brain. Penny grows curious about Leonard's feelings about marriage when Bernadette asks Howard to sign a pre-nuptial agreement
After Sheldon keeps Leonard awake all night, Leonard decides to break the Roommate Agreement with Sheldon. Howard makes preparations to go on a flight to the International Space Station and enlists Raj's help to ensure he gets a cool astronaut nickname
Leonard and Penny continue testing their rekindled relationship using an innovative system to report their discrepancies. Howard and Bernadette begin to worry when Raj starts treating his new phone like a person, while Sheldon and Amy try to achieve internet fame by creating a video podcast about flags
Leonard asks Penny out on a date, and they agree to give their relationship another chance. They soon begin to remember why it did not work out in the first place, but end up sleeping together anyway. The 100th episode of the comedy, starring Johnny Galecki and Kaley Cuoco
Sheldon is uninterested in Amy's career, so Penny, Raj and Leonard try to make him understand that sometimes it benefits a relationship to pretend to care about a partner's accomplishments. Howard notices Bernadette is uncomfortable around children when she helps him perform a magic show at his nephew's birthday party
Leonard confronts the man who tormented him in high school, while Penny realises she did her fair share of bullying in the past and calls the people she targeted to apologise. Comedy, starring Johnny Galecki and Kaley Cuoco
Comic-book store owner Stuart asks Amy out on a date, forcing a jealous Sheldon to consider the future of his relationship with her. Meanwhile, the scientists become obsessed with an unusual new card game, and Penny organises a round of Twister. Comedy, starring Jim Parsons and Mayim Bialik
Leonard and Penny endure an awkward night at the cinema, with both of them insisting the outing is not a date. Meanwhile, a terrified Sheldon enlists his friends' help when a bird flies into his apartment, but his behaviour soon leaves them exasperated. Comedy, starring Johnny Galecki, Kaley Cuoco and Jim Parsons
Amy is hurt when she discovers Penny and Bernadette went shopping for bridesmaid dresses without. She first turns to a reluctant Sheldon for comfort and later tries to drown her sorrows Comedy, starring Mayim Balik and Katey Cuoco
Leonard has doubts about his feelings for Priya when he kisses a girl he meets in the comic-book store, while the rest of the gang members play pranks on Sheldon in celebration of Halloween. Comedy, starring Johnny Galecki and Jim Parsons
Sheldon's mother comes to visit and woos the gang, but he cannot help feeling jealous of all the attention she is receiving - until a bout of illness lays him low, and he suddenly sees the benefits of having her around. Comedy, starring Jim Parsons
Sheldon's old adversary Wil Wheaton returns and invites everyone to a housewarming party. Leonard is eager to go, but Sheldon threatens to shun him if he attends. However, he soon changes his mind when he finds out that Star Trek: The Next Generation actor Brent Spiner will also be there
Raj feels upset about not being in a relationship, so Penny sets out to find a date and introduces him to a girl he can actually talk to. They hit it off, but when it becomes apparent he has been buying his new girlfriend large amounts of expensive gifts his friends become suspicious she is only interested in his wealth
Leonard inadvertently gives the impression he is attracted to Amy when he goes as her date to her colleague's wedding. Meanwhile, Howard tries to persuade Bernadette they should live with his mother after getting married and suggests a trial run of the arrangement over the weekend
Amy is caught in a battle of wills between Sheldon and Penny, while Leonard tries to reignite his long-distance relationship with Priya, who has moved back to India. Comedy, starring Johnny Galecki, Kaley Cuoco and Jim Parsons
Penny worries about the consequences of spending the night with Raj, and Leonard's reaction confirms her worst fears. Meanwhile, Sheldon is more interested in the upcoming paintball competition, and tries to refocus the boys' attentions as they argue over the previous evening's activities. Comedy, starring Jim Parsons, Johnny Galecki and Kaley Cuoco
Bernadette receives her PhD, and the friends then tease Howard about being the only one among them who is not a doctor. Meanwhile, Raj becomes Sheldon's new flatmate after overhearing Leonard and Priya engaging in a Star Trek bedroom fantasy. Comedy, starring Johnny Galecki, Jim Parsons and Kunal Nayyar
Howard decides to tell his mother that he and Bernadette are engaged - but she later collapses, making him fear the shock of the news has caused her to suffer a heart attack. As the gang convenes at the hospital, Sheldon's fear of infectious diseases lands him in trouble, while Priya and Penny bond over coffee
Amy and Penny ask Bernadette to help them spy on Leonard and Priya after the couple invite her and Howard to dinner. An experimental drug helps Raj overcome his fear of talking to women, but the cure proves more effective than he had hoped. Comedy, starring Johnny Galecki and Jim Parsons
Sheldon is infuriated when Priya uses her legal knowledge to find a loophole in the room-mate agreement - but his spirits are lifted by a night on the town with Amy, Penny and Bernadette. Comedy, starring Jim Parsons, Johnny Galecki and Kaley Cuoco
Amy and Sheldon start a gossip experiment to see how quickly rumours spread among the gang, while Howard tells his friends that he is planning to propose to Bernadette - not realising Raj is wrestling with his own feelings for her. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Sheldon is distraught when his online gaming account is hacked, so his friends decide to find out who is responsible. However, they make the disastrous mistake of confronting the culprit in person. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco
Leonard faces the difficult decision of choosing between his relationship with Priya and his friendship with Penny. Meanwhile, Howard impresses his friends with a magic trick - and an exasperated Sheldon is determined to figure out how he did it. Comedy, starring Johnny Galecki and Jim Parsons
Sheldon decides to make a new set of friends as he is depressed that the group's social world revolves around Leonard rather than himself. Meanwhile, Amy and Bernadette try to persuade Penny to go on a date. Comedy, guest starring LeVar Burton (Star Trek: The Next Generation), with Johnny Galecki, Jim Parsons and Mayim Bialik
Wolowitz is torn between taking his relationship with Bernadette to the next level and pleasing his mother - and the solution he comes up with leaves everyone unsatisfied. Leonard rekindles his romance with Raj's sister Priya, while Amy uses Penny's emotions as the basis for a research project
Leonard is forced to consider how far he is willing to push himself in the name of science when a wealthy benefactor makes an indecent proposal. Comedy, starring Johnny Galecki, with Jessica Walter (Arrested Development) and Joshua Malina (The West Wing)
Sheldon agrees to participate in a series of short lectures at the university, but is worried the students dislike him. On Amy's guidance, he asks Penny to give him acting lessons to help him engage with his audience. Elsewhere, Koothrappali fantasises about his best friend's partner. Comedy, starring Jim Parsons
Tensions run high when the gang attends a weekend science conference. Wolowitz becomes argumentative after Bernadette runs into a former boyfriend, and the fallout causes chaos with the hotel room arrangements. Comedy, guest starring Rick Fox, with Simon Helberg and Melissa Rauch
Leonard's ingenious idea for a new smartphone application puts pressure on his friendship with Sheldon, who fights with him for control of the project. Comedy, starring Johnny Galecki and Simon Helberg
The guys have fun at the expense of Penny's boyfriend Zack, but later try to make amends by enlisting his help with the New Year's costume competition at the comic-book store. Comedy, starring Kaley Cuoco and Simon Helberg
Amy finds she has romantic feelings for Penny's former boyfriend Zack, while Raj and Howard begin competing to prove which of them would make the better superhero. Comedy, guest starring Brian Thomas Smith
Penny's dad pays a visit and Leonard discovers she told her parents they were back together, so he plays his boyfriend role to the hilt - much to her dismay. Meanwhile, Raj gets drunk and makes a pass at Howard's girlfriend Bernadette. Guest starring Keith Carradine (Dexter)
The friends set up camp outside a cinema to get tickets for a new cut of Raiders of the Lost Ark - but find themselves resuming hostilities with Sheldon's old foe Wil Wheaton, the former Star Trek: The Next Generation actor. Meanwhile, Penny and Bernadette invite Amy to a sleepover
Leonard vows to be more self-assured around women, believing his problem attracting a girlfriend stems from a lack of confidence. An FBI agent interviews the gang to assess Howard's suitability for a team working on a new surveillance satellite. Guest starring Eliza Dushku (Dollhouse)
Raj's sister Priya visits the gang, causing tension when Leonard tries to cover up the fling he once had with her. After discovering his friend's secret, Sheldon struggles to keep quiet, leading the guys to reveal information they have all been keeping from one another
Leonard is depressed that everyone seems to be paired off except him, and resorts to desperate measures to get a girlfriend. Meanwhile, Sheldon looks for a way out of his relationship with Amy, who wants him to meet her mother. Comedy, starring Johnny Galecki and Jim Parsons
An embarrassing secret from Wolowitz's past comes to light as he tries to win back ex-girlfriend Bernadette, while Sheldon and Raj engage in a battle of wills when they have to work in the same office space. Guest starring Katee Sackhoff (Battlestar Galactica) and George Takei (Star Trek)
Sheldon breaks up with Amy, and turns to the feline world in his search for an alternative to human companionship. However, when he starts to bulk-buy pet cats, Leonard decides enough is enough, and calls for reinforcements to help bring his friend back to his senses. Comedy, starring Jim Parsons
Sheldon tries to extend his lifespan when he realises he will not be around long enough for his consciousness to be downloaded into a robot body, and the friends encounter Apple co-founder Steve Wozniak (guest starring as himself) at the Cheesecake Factory
Penny is stunned when Sheldon announces he is about to go on his first-ever date, and is even more surprised to find herself tagging along. Meanwhile, Leonard and Raj take a trip to the hospital after Wolowitz's new robotic arm creates problems
Raj and Howard register Sheldon with an online dating site and find his perfect woman, who appears to be his female equivalent. Meanwhile, Penny gets drunk and seduces Leonard, but she regrets it the next day. Comedy, starring Johnny Galecki, Jim Parsons and Kaley Cuoco. Mayim Bialik (Blossom) joins the cast
The comedy flashes back to reveal how Sheldon saved the lives of his pals, and looks at the origins of his friendship with Leonard seven years previously, as well as explaining the housemates' agreement. Comedy, starring Johnny Galecki and Jim Parsons
Sheldon invites a famous physicist to the flat after befriending her online, but is put out to find Leonard showing an interest in her. Meanwhile, Penny has to confront her boyfriend when the visitor turns up in his bedroom. Guest starring Judy Greer (Glenn Martin, DDS)
Sheldon tries to hide the fact he had dinner with Penny after she broke up with Leonard, hoping to stay friends with her. However, keeping secrets does not prove to be his area of expertise, and it is not long before for his double life is exposed. Comedy, starring Jim Parsons, Kaley Cuoco and Johnny Galecki
Leonard tells Penny he loves her, but fails to get the response he would have liked. Sheldon also finds himself competing against Star Trek: The Next Generation actor Wil Wheaton once again when the gang goes bowling - and tries to get his revenge
Sheldon is awarded a prestigious prize by the university but worries about the speech he will have to make when collecting the award so Penny and Koothrappali try to build up his confidence - with little success
The friends fight over a ring they believe was used in The Lord of the Rings. Leonard hopes to return the item to its rightful owner - but Raj wishes to sell it so he can buy a jet ski, and Sheldon takes on the persona of Gollum when he becomes obsessed with the piece of jewellery
Sheldon misses an opportunity to meet Spiderman creator Stan Lee when he has to go to court for driving through a red light while taking Penny to hospital, and his anger at the inconvenient timing leads to him being imprisoned. Feeling guilty, Penny finds out the address of the man behind the superhero and takes Sheldon there - but his troubles with the law have yet to reach their conclusion and the visit does not go as expected
When Leonard is invited to see the world's largest particle accelerator in Switzerland, he asks Penny to join him as a Valentine's Day treat - much to the disappointment of Sheldon, who tries to persuade the couple to allow him to take her place
Sheldon develops a mental block and has difficulty working on a formula, so in a move inspired by Albert Einstein he gets a job at the Cheesecake Factory diner to try to revive his creativity - and despite Penny's objections, proves surprisingly effective in the role. Guest starring Yeardley Smith (The Simpsons)
Leonard and Sheldon's flat is burgled, so they work on a state-of-the-art security system in a bid to outwit any future would-be thieves. However, their plans go awry when they ensnare Penny in a net. Comedy, starring Johnny Galecki and Jim Parsons
Raj lusts after a girl he meets while attending a university party with Sheldon, and Leonard lives to regret airing his disapproval of Penny's belief in psychics. Comedy, starring Kunal Nayyar and Jim Parsons
When his mother turns up unannounced, Leonard's horror turns to anger when he learns Sheldon knew about the visit - and his parents' divorce - before him. After going out drinking with Penny, Leonard's mother and Sheldon kiss. Guest starring Christine Baranski (The Good Wife)
Thursday 25th December 11:00pm EST - WNYW (FOX)
Wolowitz accuses Leonard of being interested in his girlfriend after Bernadette shows interest in his experiments, while Penny is also jealous and asks Sheldon to teach her physics so she can discuss Leonard's work with him. Johnny Galecki, Simon Helberg and Kaley Cuoco star
Howard starts avoiding Bernadette after his fears grow about committing to her, but he soon realises he has made a mistake and tries to compensate for it. Meanwhile, Kripke plays a prank on Sheldon during a radio interview, and the victim finds himself caught out by the Dean when he tries to get revenge. Johnny Galecki, Simon Helberg and Kaley Cuoco star, with an appearance by Katee Sackhoff (Battlestar Galactica) as herself
Leonard, Rajesh and Howard go camping to watch the Leonid meteor shower, but the trip takes an unexpected turn thanks to some specially baked cookies. Meanwhile, Penny injures herself when she slips in the shower, and with the rest of the gang out of town, it is left to Sheldon to come to her aid
A jealous Leonard argues with Penny when she invites one of her male friends to stay at her apartment while he is in town. Unfortunately, the row brings up unpleasant memories for Sheldon of watching his warring parents, causing even more tension between the friends. Johnny Galecki, Kaley Cuoco and Jim Parsons star
Leonard worries his lack of American football knowledge is alienating him from Penny and her friends. However, he finds an unlikely sporting tutor in the form of Sheldon, who reluctantly spent most of his childhood attending games with his father. Meanwhile, Raj is infuriated when Howard abandons him to pursue a girl at a kite-fighting contest
Sheldon is given the chance to square off against the one actor from the Star Trek franchise he holds a grudge against - Wil Wheaton. Meanwhile, Leonard asks Penny to set Howard up on a date with one of her friends. Comedy, starring Johnny Galecki and Jim Parsons
Raj accepts Sheldon's offer to work for him as he is desperate to avoid being sent back to India. Howard starts spending more time with Leonard and Penny, who would rather be left alone. Johnny Galecki, Simon Helberg and Kaley Cuoco star
Leonard tries to mould Penny into his dream woman and rewards her with chocolate when she does things he approves of - in the hope that she will keep doing them. Meanwhile, Howard and Raj meet two women at a goth nightclub, and things appear to be going well until the ladies take them to a tattoo shop
Sheldon and Howard stake their most highly prized comic books on a bet to determine the species of a cricket, while Leonard and Penny struggle to recover from an awkward first night together. Johnny Galecki, Simon Helberg and Kaley Cuoco star
Sheldon returns to Texas in disgrace when he discovers his friends tampered with the Arctic expedition data after growing tired of his quest for a scientific breakthrough. Leonard becomes frustrated when constant interruptions affect his attempts to woo Penny, but his mood improves when the pair finally sleep together
Sheldon wins a grant to pay for a summer expedition to the North Pole, and invites his friends to join him. However, the gang's imminent departure causes Leonard and Penny to reconsider their feelings for each other. Johnny Galecki and Kaley Cuoco star
Stuart takes Penny out for a second date, during which she drunkenly reveals her true feelings. Meanwhile, Wolowitz uncovers a flaw in the toilet he designed for a Nasa space shuttle, and enlists the aid of friends to correct it before the craft is launched. Kaley Cuoco, Kevin Sussman and Simon Helberg star
Sheldon is forced to spend the night at Penny's after accidentally locking himself out of his own apartment. Meanwhile, Leonard and Raj take a heartbroken Wolowitz to Las Vegas to cheer him up, where they pay a prostitute to take an interest in their downhearted friend. With guest star Jodi Lynn O'Keefe (Prison Break)
Penny catches the eye of a comic-book shopkeeper, and Leonard is devastated when she gives serious consideration to dating her new admirer. Desperate for help, Leonard enlists Sheldon to discredit his love rival by preying on his obsessive enthusiasm with Batman. Johnny Galecki, Kaley Cuoco and Kevin Sussman star
Penny feels threatened when another sexy woman, who has landed a role in TV series CSI, moves into the apartment building, and gradually begins to sense that her friends are being manipulated by the new arrival. Comedy, starring Kaley Cuoco, Valerie Azlynn, Johnny Galecki and Simon Helberg
Penny starts her own hair accessories business and the orders start to pile in. However, she makes the mistake of asking Sheldon to help, leading to frustration and regret. Comedy, starring Jim Parsons and Kaley Cuoco
While travelling to San Francisco, Leonard, Sheldon, Wolowitz and Raj discover actor Summer Glau is sharing a train with them. Desperate to discuss the Terminator TV series with her, the friends devise a series of plans to engage her in conversation. With Johnny Galecki, Simon Helberg, Jim Parsons and Rajesh Nayyar
Sunday 28th December 9:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Tensions between Sheldon and Penny reach an all-time high after a paintballing accident leaves an ugly stain on the awkward physicist's favourite couch cushion. Meanwhile, romance blossoms between Leslie and Wolowitz. Jim Parsons and Kaley Cuoco star
Sunday 28th December 9:00pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Leonard and Penny share an intimate moment as they recover from receiving a psychological deconstruction from the physicist's emotially distant mother, an expert in psychiatry and neural sciences. Guest starring Mamma Mia! actor Christine Baranski
Sunday 28th December 8:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Penny runs into money troubles, so Sheldon offers to lend her some cash to help her pay the rent. However, when Leonard discovers that his neighbour's former boyfriend Kurt is the cause of her financial woes, he gathers the gang for a confrontation. Starring Jim Parsons, Johnny Galecki and Kaley Cuoco
Sunday 28th December 8:00pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Sheldon decides to put his formidable brain power to use in formulating a scientific procedure for making friends. However, to prove his findings, he must first win the trust of fellow scientist Barry Kripe to gain access to his powerful computer. Comedy, starring Jim Parsons and John Ross Bowie
Today at 9:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Sheldon and the gang are excited when Barry Kripke challenges them to a robot duel and they cannot wait to start building their 'killer' machine called Monte. Meanwhile, Penny confronts Wolowitz about his crude behaviour toward women. Guest starring John Ross Bowie
Today at 9:00pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Sheldon's obsession with gift-giving etiquette annoys his friends as Christmas approaches. Meanwhile, Leonard is thrilled to meet an award-winning scientist, only to be filled with jealousy when his new colleague takes an interest in Penny. With guest star Michael Trucco (Battlestar Gallactica and One Tree Hill)
Thursday 25th December 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Leonard turns to Penny for advice when his relationship with Stephanie takes off faster than he would have liked, and he realises he is the last person to notice that she has moved in with him. Comedy, starring Johnny Galecki and Kaley Cuoco
Today at 8:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Sheldon is delighted that Leonard has finally managed to find a girlfriend who meets his high standards, but his over-exuberance looks set to cause problems. Jim Parsons and Johnny Galecki star
Today at 8:00pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
A smitten Wolowitz becomes convinced he has met his soul-mate in the form of Stephanie Barnett, a distinguished resident surgeon. However, he fails to realise that the object of his affections is far more interested in Leonard. Less Than Perfect's Sara Rue guest stars
Penny begins visiting the boys' flat to watch her favourite shows after her TV breaks down. However, when Sheldon tires of her presence he bans her from his home, only for her to seek an embarrassing form of vengeance. Meanwhile, Howard and Raj search for the America's Next Top Model house
Thursday 1st January 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
An obsessive student takes a shine to Sheldon, and before he knows what has happened, the misanthropic physicist finds himself with a girlfriend. However, his new partner quickly expresses distaste toward his social life, and removes him from his limited circle of friends by forcing him to work on a troublesome scientific problem. With guest star Riki Lindhome
Wednesday 31st December 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Sheldon is forced to confront his fear of driving when both Penny and Howard refuse to give him a lift to work. Desperate to be free of the obligation, Leonard and the gang intervene to discover why the physicist never learned to drive. Comedy, starring Jim Parsons and Johnny Galecki, with Octavia Spencer (The Help)
Tuesday 30th December 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Leonard encourages Howard and Sheldon to be supportive when Raj is named one of People magazine's '30 to Watch Under 30'. However, when Raj makes a pass at Penny, Leonard struggles to maintain a positive perspective on his friend's new-found confidence. Kunal Nayyar and Kaley Cuoco star, with a guest appearance by Charlie Sheen
Monday 29th December 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Penny becomes addicted to an online game based on the world of Conan the Barbarian. As her obsession intensifies, she begins to neglect her friends, and seeks, instead, the company of the usually snide Sheldon whom she continually pesters for advice. Starring Kaley Cuoco and Jim Parsons
Friday 26th December 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Leonard is dejected to see Penny with another man and decides to cut his losses by going back to fellow scientist Leslie Winkle - a move that upsets Sheldon. Starring Johnny Galecki, Kaley Cuoco and Sara Gilbert
Wednesday 24th December 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Sheldon finds himself forced to keep a secret when Penny decides to confide in him about what happened on her disappointing first date with Leonard. Comedy, starring Johnny Galecki, Kaley Cuoco and Jim Parsons
Tuesday 23rd December 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
Following the break-up of Penny's relationship, Leonard finally summons up the courage to ask her out. When she accepts, each of them separately asks Sheldon for advice on how to handle the forthcoming date. Last in series, starring Johnny Galecki, Kaley Cuoco and Jim Parsons
Tomorrow at 7:30pm EST - WWOR TV Channel 9 (Local New York) (MyNetworkTV)
When Penny finds out Leonard's family never celebrated his birthdays she enlists Sheldon's help to organise him a surprise party, while Wolowitz gets him out of the way by staging an emergency hospital visit. Kaley Cuoco and Johnny Galecki star
All Sheldon's friends fall for his sexy twin sister, who has arrived to pay him a visit, but he declares he will have the final say on who can date her - an announcement that particularly dismays Leonard. Comedy, starring Johnny Galecki and Jim Parsons
Penny makes fun of Leonard's habit of collecting sci-fi memorabilia, so he decides to give it up - but his friends object and do everything possible to persuade him not to change his ways. Comedy, starring Johnny Galecki and Kaley Cuoco
The gang kicks Sheldon out of the physics bowling team and replace him with Leslie, so he decides to try and prove his superiority by forming a rival squad of his own. Johnny Galecki, Jim Parsons and Kaley Cuoco star
Sheldon feels threatened when he meets a 15-year-old physics prodigy who is even smarter than he is, so Leonard agrees to help him discredit the precocious youngster's research. Johnny Galecki, Simon Helberg and Kaley Cuoco star
Sheldon falls ill, and his friends decide to go to a Planet of the Apes movie marathon to keep their distance, knowing he will be in a terrible mood. However, an unsuspecting Penny offers to nurse him. Comedy, starring Johnny Galecki, Simon Helberg and Kaley Cuoco
Sheldon and Leonard invent excuses to avoid having to attend Penny's performance in a production of the stage musical Rent, but maintaining the pretence becomes increasingly complicated. Johnny Galecki, Simon Helberg and Kaley Cuoco star, with DJ Qualls (Road Trip)
Leonard and Sheldon receive an invitation to present their research to a physics conference, but Sheldon's reluctance to pander to his peers causes conflict between the friends - with Penny's intervention only making matters worse. Johnny Galecki and Jim Parsons star
Raj's parents set him up on a blind date in the hope of initiating an arranged marriage, but after a promising start it becomes apparent that the girl in question is more interested in Sheldon. Meanwhile, Penny begins her new job as a bartender. Starring Kunal Nayyar and Jim Parsons
Howard hooks up with one of Penny's promiscuous friends, prompting the guys to fly into a panic and enlist their neighbour to make up the numbers to play a video game. Starring Simon Helberg, Kaley Cuoco and Johnny Galecki
Penny hosts a Halloween costume party, which proves to be a worthy test for Leonard, Sheldon, Howard and Raj's social skills. During the event, Leonard has a run-in with Penny's ex-boyfriend. Kaley Cuoco, Johnny Galecki and Simon Helberg star
Leonard fears he is wasting his time with Penny and ends up spending the night with fellow scientist Leslie. However he is disappointed when she later tells him she was only interested in a one-night stand. Meanwhile, Sheldon frets over a variation to his hamburger routine. Starring Johnny Galecki, Kaley Cuoco and Jim Parsons
Sheldon is fired for being disrespectful to his boss, and explores new activities in a bid to find a purpose in life other than physics, but Leonard takes drastic action to restore him to his old self. Laurie Metcalf (Desperate Housewives) guest stars as Sheldon's mother
Thursday 1st January 10:30pm EST - Turner Broadcasting System
Leonard is upset to learn Penny is dating someone, so his friends and fellow scientists encourage him to seek a new romance by asking another woman out. Guest starring Sara Gilbert (Roseanne), with Johnny Galecki and Kaley Cuoco
Thursday 1st January 10:00pm EST - Turner Broadcasting System
Leonard enlists his room-mate's help when he agrees to drop off a parcel for new neighbour Penny, but when Sheldon sees how messy her room is, he attempts to do a good deed which is not well received. Johnny Galecki, Jim Parsons and Kaley Cuoco star
Thursday 1st January 9:30pm EST - Turner Broadcasting System
Comedy about two friends who understand more about the laws of physics than they do about interacting with other people. When a free-spirited beauty called Penny moves in next door, Leonard is immediately smitten with her, but Sheldon warns him he runs the risk of a broken heart if he tries to romance her. Johnny Galecki, Simon Helberg and Kaley Cuoco star
Wednesday 31st December 10:30pm EST - Turner Broadcasting System
Rick Edwards celebrates the 100th episode of the American comedy by taking a look back at some of the show's most memorable scenes. He meets members of the cast and crew on-set in Hollywood, where they share their own favourite moments, and reveal a selection of behind-the-scenes secrets
An evening of special programming to celebrate the 100th episode of the sitcom, beginning with Rick Edwards travelling to Hollywood for a behind-the-scenes visit to the comedy's set, catching up with the cast and learning everything there is to know about the show
Leonard y Wolowitz se enfrentan por una emergencia en el trabajo; Amy y Sheldon hacen una fiesta de Navidad estilo victoriano.
En este episodio de The Big Bang Theory, Howard, Leonard y Raj repasan la investigación de su profesor fallecido.
A Leonard le hacen una pequeña operación en la nariz; Bernadette y Howard intentan mejorar su matrimonio.
Sheldon se siente presionado a participar en el baile de fin de curso que preparan los chicos en el tejado.
Los chicos intentan ayudar a Penny cuando tiene un dilema en su trabajo; Bernadette y Amy hablan sobre sexualidad y mujeres científicas.
Raj y Sheldon intentan hacer una simulación de una expedición; Después de una discusión sobre dinero, Penny y Leonard les piden consejo a Bernadette y a Wolowitz.
Bernadette y Amy acusan a Penny de ser una agua fiestas durante su fin de semana en Las Vegas; Los chicos tratan de inventar algo grandioso.
La honestidad de Raj lo acosa cuando su nueva novia trata a Penny fríamente; los chicos piensan convertirse en socios de Stuart.
Wolowitz se siente nervioso cuando se le pide que tire la primera bola en un juego de los Angelinos de Los Ángeles; Penny y Leonard quieren demostrarle a Sheldon que está equivocado al decir que él y Amy son la mejor pareja.
Cuando Sheldon tiene que enseñar una clase, Howard decide tomarla; Amy aprovecha la tensión entre Penny y Bernadette.
Un mal día obliga a Penny a re-evaluar sus opciones - incluyendo a Leonard; Bernadette y Howard deben cuidar a la señora Wolowitz; Sheldon ofrece consejos sobre relaciones a Raj.
El profesor Proton ayuda a Sheldon a lidiar con el dolor; Leonard inicia una competencia con Penny; Bernadette y Amy preparan un regalo del día de 'La Guerra de las Galaxias' para los chicos.
Sheldon da espontaneidad a un intento, lo cual causa fricción inesperada para Penny, Bernadette y Amy; Raj pide ayuda con la preparación de una cita con Emily Howard.
Sheldon tiene una crisis personal cuando decide que la Teoría de cuerdas es una perdida de su tiempo; una cita doble termina en vergüenza para Howard.
Ante un futuro incierto, Sheldon considera un cambio importante; Emily y Raj deciden llevar las cosas al siguiente nivel.
Leonard y Amy hacen un viaje inesperado a Arizona para buscar a Sheldon; Penny tiene una entrevista de trabajo en Barnadette's Company; la relación entre Stuart y Mrs. Wolowitz perturba a Howard.
Raj lucha contra la culpa cuando sale con dos mujeres a la vez; Penny tiene la oportunidad de estar en una película.
Sheldon se enfrenta a una nueva realidad cuando él visita a su mamá en Houston; una fiesta misteriosa provoca discusiones.
Bernadette intenta negociar la paz entre Sheldon y Wolowitz; Penny recibe una oferta vergonzosa; Raj quiere que Amy le escriba a una mujer en su nombre.
Cuando Leonard compra una mesa para el comedor, Sheldon vuelve a evaluar los cambios en su vida; Bernadette se desgarra cuando Wolowitz tiene la oportunidad de regresar al espacio.
Sheldon y Amy salen de viaje a un viñedo con Howard y Bernadette; Penny y Leonard llevan al perro de Raj al veterinario.
Incapaz de obtener boletos para Comic-Con, Sheldon intenta organizar su propia convención y termina pasando una noche salvaje con James Earl Jones; las damas intentan actuar maduramente.
Sheldon debe aprender a relajarse cuando él se ve obligado a tomar unas vacaciones; Leonard intenta apoyar a Penny cuando ella renuncia a su trabajo; Bernadette necesita reemplazar uno de los cómics de Stuart.
Mientras Leonard intenta ayudar a Penny con una decepción, Penny le hace una pregunta contundente acerca de su relación; Sheldon quiere aprender a ser divertido.
Mientras Sheldon está en Texas, el resto del grupo se da cuenta de lo mucho que él ha cambiado sus vidas mientras decoran el árbol de Navidad del departamento.
Amy y Leonard intentan ayudar a Sheldon a superar su vergüenza; Raj se queda con Bernadette y Howard durante una semana.
Cuando el grupo decide pasar el Día de Acción de Gracias en la casa de la Sra. Wolowitz, Sheldon protesta; Leonard y Penny se enfrentan a un error de su pasado.
Sheldon hace que Leonard camine una milla con sus zapatos cuando sale a la luz un error; Penny decide confrontar a la ex de Raj.
El último avance científico de Sheldon lo deja sintiéndose como un fraude; un gesto romántico entre Howard y Bernadette causa que Penny aumente su juego con Leonard.
La relación de Sheldon y Amy es puesta a prueba cuando ella acepta un trabajo en la universidad; una pelea con Bernadette provoca que Howard tenga que dormir en el sillón de Raj.
Cuando el profesor Proton le pide ayuda a Leonard con un experimento, Sheldon se venga haciéndose amigo del rival de Proton, Bill Nye.
Sheldon quiere vengarse después de que Amy arruina uno de sus filmes favoritos; Leonard descubre una forma para que Penny no haga nada; Stuart y Raj hacen perfiles para tener citas en línea.
Raj diseña una búsqueda del tesoro que saca lo mejor -- y lo peor -- en todo el grupo.
La amistad de Leonard y Sheldon es puesta a prueba; la relación de Wolowitz con su mamá causa una amenaza a su masculinidad.
Sheldon y Penny comparten secretos mientras Leonard no está; Wolowitz ayuda a Raj con su ex.
La relación de Amy y Sheldon da un giro sorprendente durante un juego de 'Dungeons & Dragons'; Lucy y Koothrappali tienen una cita muy incómoda.
Leonard y Sheldon contratan al conductor de su programa de televisión favorito de la infancia para que actúe; Bernadette y Howard se meten en problemas mientras cuidan al perro de Raj.
Amy intenta ayudar a Sheldon a superar su necesidad compulsiva cuando uno de sus programas favoritos de televisión es cancelado; Raj descubre un secreto acerca de Lucy.
Cuando Leonard recibe una oportunidad de trabajo para laborar en Europa, Penny y Sheldon son sorprendidos.
Las chicas se involucran cuando Leonard, Sheldon y Raj compiten por la permanencia en universidad.
Howard considera si debe o no abrir una carta de su padre; Penny y Leonard son anfitriones en un cóctel para adultos.
Leonard, Sheldon y Wolowitz hablan con chicas de secundaria acerca de carreras relacionadas con la ciencia; Raj planea una cita con Lucy.
Los habilidades de actuación de Penny impresiona a Sheldon.
Los chicos buscan un regalo perfecto de Día de San Valentín para sus personas allegadas; Stuart y Raj realizan una fiesta de 'gente solitaria' en la tienda de libros de historieta.
Sheldon y Leonard se pelean; Raj ayuda Sra. Wolowitz.
Sheldon se enfrenta a una crisis de confianza cuando se ve obligado a trabajar con su némesis, Barry Kripke.
Mientras los chicos usan disfraces y viajan por carretera a una convención de cómics, las damas deciden quedarse en casa e intentan interpretar un libro de historietas.
Cuando Sheldon es acusado de acoso sexual, él termina provocándoles muchos problemas a Raj, Leonard y Wolowitz.
Sheldon recuerda la Navidad durante un juego; Amy, Penny y Bernadette le buscan una cita a Koothrappali.
Amy se enferma y Sheldon intenta cuidarla mientras se recupera; Wolowitz y su suegro planean un viaje de pesca.
La pelea de Sheldon y Wolowitz por un lugar de estacionamiento en la universidad impacta al grupo.
Raj y Howard intentan descubrir por qué Sheldon desaparece cada tarde a las 2:45; los celos aumentan en la relación de Penny y Leonard.
Bernadette quiere que Wolowitz se salga de la casa de su mamá; Sheldon está atrapado en medio de la discusión entre Amy y Wil Wheaton.
Un juego amenaza la relación de Sheldon con Stephen Hawking; Penny se inscribe en secreto para una clase universitaria.
El grupo se dirige a la tienda de libros de historietas de Stuart para celebrar Halloween; Leonard usa la ciencia para seducir a Penny.
El regreso de Wolowitz del espacio no es todo lo que él esperaba; juego se convierte en una guerra.
Sheldon intenta intervenir cuando él descubre que Penny está pensando terminar su relación con Leonard; Howard is picked on.
Amy se siente amenazada por la nueva asistente de Sheldon; Wolowitz empieza a sentir las presiones de estar en el espacio.
Raj enfrenta su soledad mientras sus amigos tienen citas; Wolowitz es arrastrado a una pelea entre Bernadette y su mamá, mientras está en el espacio.
Planes de boda son puestos en peligro cuando NASA cambia la fecha de su viaje espacial; Penny es sorprendida por la propuesta de Leonard.
La historia sexual de Howard hace reconsiderar a Bernadette sobre su futuro juntos.
Ganga organiza la boda de Wolowitz y Bernadette, antes que él parta para su viaje al espacio.
Cuando Wolowitz trabaja con Stephen Hawking, Sheldon esta decidido a concer al científico famoso.
Tras recibir una pieza de colección de Viaje a las Estrellas, Sheldon se encuentra acosado por el Sr. Spock.
Sheldon planea un maratón de videojuegos con los chicos en vez de asistir a la fiesta de la tía de Amy.
La rutina de Sheldon es interrumpida cuando su peluquero se enferma; Wolowitz duda sobre su decisión de ir al espacio.
Sheldon y Kripke compiten por una oficina; Penny recibe un regalo de Amy.
Sheldon trabaja con Amy en su laboratorio cuando la universidad lo obliga a tomar una vacación.
Leonard empieza a reconsiderar su amistad con Sheldon; Wolowitz intenta elegir un apodo de astronauta.
Penny y Leonard experimentan con su nueva relación; Raj forma una relación con su asistente telefónico virtual.
Todo puede cambiar cuando Leonard invita espontáneamente a Penny a una cena romántica.
Leonard debe enfrentarse a un acosador que lo atacó en la preparatoria.
Sheldon está celoso cuando Stuart (Kevin Sussman), un chico de la tienda de libros de historietas, le pide una cita a Amy.
Leonard y Penny pasan un tiempo solos; Sheldon intenta enfrentar su miedo a los pájaros.
Amy está devastada cuando Penny y Bernadette compran vestidos de novia sin ella.
Sheldon compite con todos sus amigos por la atención de su madre (Laurie Metcalf) cuando ella está de visita.
Una atractiva arista de los libros de historietas prueba la relación de Leonard y Priya; Sheldon intenta asustar a sus amigos.
Wil Wheaton invita a Leonard y Sheldon a una fiesta en su casa; Howard recibe una oportunidad.
Penny presenta a Raj con mujer con quien puede comunicarse.
Amy y Leonard intentan conocerse mejor; Bernadette, Howard y la Sra. Wolowitz pasan el fin de semana juntos.
Penny está preocupada porque ha arruinado su relación con sus amigos; Sheldon toma mando del equipo de paintball.
Amy está atrapada en medio de una pelea cuando Penny y Sheldon discuten por una silla; Leonard intenta que su relación a larga distancia sea más emocionante.
Bernadette recibe su doctorado, inspirando a los chicos a que molesten a Wolowitz por su falta de un título.
Mamá de Howard termina en el hospital después de escuchar noticias de su compromiso con Bernadette.
Raj intenta curar su ansiedad social; Penny espía a Leonard y a su novia a través de Bernadette.
Priya analiza el acuerdo con su compañera de cuarto; las damas sacan a bailar a Sheldon.
Amy y Sheldon difunden chisme como parte de un experimento; Howard decide dar un gran paso en su relación con Bernadette.
Los chicos intentan averiguar quién robó la cuenta del juego en línea de Sheldon.
Leonard tiene que elegir entre Penny y su nueva novia, Priya; el truco de magia de Howard enloquece a Sheldon.
Sheldon se molesta cuando se entera que Leonard es el centro de su grupo de amigos.
Wolowitz considera llevar las cosas con Bernadette al siguiente nivel; Leonard y la hermana de Raj reinician su relación.
Un donador rico hace que Leonard se cuestione lo que él quiere hacer por la ciencia.
Sheldon toma clases de actuación con Penny con la esperanza de ser un mejor maestro; Koothrappali fantasea acerca de la novia de su amigo.
Bernadette se encuentra con su ex-novio (Rick Fox) mientras asiste a evento de ciencia con Wolowitz.
La idea de Leonard para una aplicación telefónica provoca una fricción en su amistad con Sheldon.
Los chicos participan en un concurso de disfraces con el nuevo novio de Penny.
Amy descubre que ella siente algo por el ex de Penny; Koothrappali y Wolowitz intentan probar quién sería un mejor super héroe.
Penny le pide a Leonard mentirle a su padre (Keith Carradine); Howard, Raj y Bernadette pasan toda una noche en un telescopio.
Los chicos acampan para ver una película; Penny y Bernadette invitan a Amy a una fiesta de pijamas.
La entrevista de Sheldon con el FBI pone en peligro la seguridad de Wolowitz.
Leonard mantiene en secreto una aventura a Sheldon, Howard y Raj.
Leonard se da cuenta de que es el único en su grupo que no tiene novia; Sheldon quiere deshacerse de su novia.
Un secreto vergonzoso de Wolowitz es revelado; Raj y Sheldon se involucran en guerra en el trabajo.
Sheldon busca una alternativa para la compañía humana y los chicos se preocupan.
Sheldon intenta alargar su vida cuando se entera que no podrá transferir su conciencia al cuerpo de un robot.
Penny analiza a la primera cita de Sheldon; Wolowitz descubre nuevo uso para brazo robótico.
Raj y Howard preparan un perfil en línea para citas por Sheldon.
Leonard le cuenta a Penny acerca de cómo conoció a Sheldon y que le pasó al elevador.
Leonard y Sheldon compiten por la atención de una física.
Sheldon se esfuerza por mantener felices a Leonard y Penny cuando ellos dejan de hablarse.
Una pelea amenaza la relación de Penny y Leonard; Sheldon y Will Wheaton se enfrentan.
El pánico escénico de Sheldon se entromete entre él y un codiciado premio.
Cuando los chicos compran un anillo de 'El Señor de los Anillos' en una venta de garaje, el articulo amenaza con separarlos.
Sheldon termina en la corte después de recibir una infracción por culpa de Penny.
Leonard debe decidir quién lo acompañará cuando él vaya a ver el Gran Colisionador de Hadrones el Día de San Valentín.
Sheldon intenta encontrar la respuesta a un problema físico trabajando con Penny.
Después de que su departamento es robado, Leonard y Sheldon buscan a sus amigos para crear un sistema de seguridad de vanguardia.
Sheldon y Koothrappali asisten a una reunión universitaria; Leonard descubre que Penny cree en los psíquicos.
Leonard está horrorizado cuando su madre (Christine Baranski) lo visita.
Sheldon trata de ayudar a Penny a entender el trabajo de Leonard; Wolowitz está celoso cuando Leonard comienza a salir con su nueva novia.
Sheldon intenta hacer las paces cuando Leonard y Penny tienen una discusión.
Sheldon desea destruir a Kripke después de ser humillado en la radio; Wolowitz intenta no destruir su nueva relación con Bernadette.
Sheldon intenta vengarse de su enemigo Wil Wheaton; Wolowitz desea que Penny le ayude con una amiga.
Penny se ve obligada a confiar en Sheldon cuando ella se lesiona, mientras Howard, Leonard y Raj están ausentes.
Sheldon le enseña a Leonard cómo entender el fútbol americano; un incidente en una competencia de papalotes amenaza la amistad de Howard y Raj.
Raj se enfrenta a la deportación si no encuentra un trabajo; Leonard y Penny tratan con Howard como una tercera opción.
Howard y Raj van a un centro nocturno Goth para conocer mujeres; Sheldon intenta modificar la conducta de Penny utilizando chocolates.
Penny y Leonard intentan recuperarse de una relación complicada; Howard y Sheldon hacen una apuesta.
Después de manipular la información de la expedición de Sheldon al Ártico, los chicos lo siguen de regreso a Texas, lo que amenaza las oportunidades de Leonard de tener un romance con Penny.
Penny hace una revelación sorprendente sobre Leonard durante su cita con Stuart; Wolowitz encuentra un desperfecto crítico de diseño en su proyecto de la NASA.
Koothrappali y Leonard llevan a Wolowitz a Las Vegas; Sheldon es encerrado con llave en su apartamento.
Wolowitz y Leonard deciden investigar un bar local en la Noche de Damas.
Penny desarrolla una rivalidad con una nueva vecina atractiva que amenaza su posición como abeja reina del edificio.
Un juego de paintball provoca una pelea entre Sheldon y Penny, y un romance entre Leslie y Wolowitz.
La solución de Sheldon para las dificultades financiales de Penny causa una confrontación entre Leonard y el ex-novio de Penny.
Cuando un dicho de Penny sobre la vida amorosa de Wolowitz se hace deprimirse, los amigos de él pierden su compañero más importante para su competición de robot.
Penny empieza salir con una colega guapo de Leonard; Leonard y sus amigos están molestados por la obsesión de Shelden de la etiqueta de dar regalos.
Leonard pide consejo de Penny cuando su relación nueva va demasiado rápido.
Sheldon está contenta cuando Leonard sale con una mujer quien tiene las calidades que Sheldon piensa ser necesarias.
Leonard sin saber sale con la mujer nueva quien Wolowitz piensa es el amor de su vida.
Mientras Leonard se prepara para una expedición de ciencia de tres meses, él y Penny reevalúan sus sentimientos de uno hacia el otro.
Cuando Sheldon corre a Penny del apartamento por una serie de infracciones, Penny intenta vengarse de él.
Sheldon y el grupo se confunden cuando una joven estudiante graduada se siente atraída por él.
Leonard y sus amigos presentan una intervención para obligar a Sheldon a enfrentar sus temores para manejar.
Raj incrementa su ego e intenta vengarse de Penny luego de ser nombrado en el artículo de una revista.
Sheldon crea a un monstruo cuando le muestra a Penny un juego en línea.
Después de ver a Penny con un joven muy apuesto, Leonard reinicia su relación con Leslie Winkle, la peor enemiga de Sheldon.
La primera cita de Penny con Leonard tiene problemas; Penny descubre que Sheldon no es un buen confidente.
El negocio de casa de Penny se vuelve en una completa pesadilla cuando Sheldon se hace cargo.
Leonard, Sheldon y Wolowitz están extasiados al enterarse de que una famosa actriz de ciencia ficción (Summer Glau) se encuentra abordo del tren a San Francisco con ellos.
Leonard y Penny se acercan después de una visita desastroso de la madre de Leonard (Christine Baranski).
Sheldon crea un procedimiento científico para hacer amigos.
Leonard idea un plan para eliminar a sus rivales cuando él, Wolowitz y Koothrappali se enamoran de la hermana gemela de Sheldon, pero su plan falla cuando Sheldon decide elegir con quién saldrá su hermana.
Cuando Leonard finalmente se arma de valor para pedirle una cita a Penny, los dos acuden con Sheldon por un consejo.
Penny descubre que Leonard no celebra los cumpleaños, por lo que ella planea una fiesta sorpresa; Sheldon inesperadamente vive una de sus más grandes fantasías en una tienda de electrónicos.
Leonard y los chicos compran una máquina del tiempo de una película clásica; Penny les cuenta a los chicos que su obsesión por los cómics y los juguetes es patética.
Cuando Sheldon trata de demostrar su superioridad mental cuando se entrenan para el Tazón de Física, los chicos lo botan del equipo.
Sheldon y Leonard buscan una manera de hacer fracasar la investigación de un prodigio de la física de 15 años de edad.
Leonard y los chicos evitan a Sheldon cuando está enfermo, dejando a Penny a su cuidado hasta que recupere la salud.
Leonard y Sheldon trata de evitar ver la interpretación de Penny después de escuchar su canción, pero la elaborada mentira de Sheldon los lleva a un inesperado resultado.
Penny intenta mediar cuando Sheldon y Leonard no están de acuerdo en presentar sus conclusiones en una conferencia de psíquicos.
Koothrappali descubre durante una cita a ciegas que puede hablar con una mujer después de algunos tragos, pero la dama se interesa en Sheldon.
Penny duerme en el sillón de Leonard y Sheldon cuando Wolowitz se apodera del departamento; los chicos le piden a Penny que se una a su equipo 'Halo'.
Leonard, Sheldon, Wolowitz y Koothrappali asisten a la fiesta de Halloween de Penny.
Leonard descubre que su persecución de Penny es infructuosa y tiene un encuentro inesperado con una compañera científica (Sara Gilbert).
Sheldon es despedido y así tiene la oportunidad de explorar la vida más allá de lo físico, pero cuando él empieza a tejer ropa y a actuar como una persona introvertida, Leonard le pide ayuda a la mamá de Sheldon.
Leonard está molesto al descubrir que Penny sale con otra persona y se arma de valor para conseguir una cita con otra mujer.
Leonard se ofrece como voluntario para firmar por un paquete, con la esperanza de provocar una buena impresión en Penny.
Leonard está feliz por conocer a su nueva vecina Penny, pero su compañero de cuarto piensa que él está persiguiendo un sueño imposible.