5 seasons available
While Howard and Bernadette welcome their new baby into the world, Amy celebrates her own birthday with Sheldon.
Sheldon and Amy visit Penny and Leonard after the holidays and tell them about their terrible trip to Texas.
Penny thinks Leonard is taking her for granted and decides to go on a spa weekend with Amy; Wolowitz and Koothrappali try to fix a squeaky floorboard in the baby's room.
Sheldon tests an MIT invention after hearing it can help him read people's emotions; Leonard finds out Penny's brother is coming to town; Raj asks his ex-girlfriends to give him dating advice.
Leonard and Wolowitz try to distract Sheldon when he slows the progress of their guidance system; Raj and Stuart look after baby Halley while Penny and Amy take Bernadette for a night out.
Sheldon and Amy have their first fight since moving in together; Koothrappali is shocked at the realities of financial independence when he stops receiving support from his father.
Cut off from his father's fortune, Koothrappali appoints Sheldon to help him get out of debt; Penny considers joining Leonard at Comic-Con.
Leonard and Penny offer Sheldon's old room to Raj after he moves out of his apartment.
Leonard, Penny and Raj settle into their new living arrangement; Sheldon expresses interest in Amy's work.
Sheldon pushes himself to the limit when he collaborates on projects with Leonard and Wolowitz as well as Amy on the same day; Bernadette nears the end of her maternity leave and must return to work.
Penny tags along on Sheldon's first date; Wolowitz finds a new use for a robotic arm.
Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.
When Sheldon searches for an alternative to human companionship, the guys become concerned.
An embarrassing secret of Wolowitz's is revealed; Raj and Sheldon get into a war at work.
Sheldon goes to extremes to keep Leonard and Penny happy when they stop speaking to each other.
Sheldon invites a famous physicist to the apartment, and competes with Leonard for her attention.
Leonard tells Penny about how he met Sheldon and what happened to the elevator.
Raj and Howard set up an online dating profile for Sheldon and find the perfect woman.
Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article.
Leonard and his friends stage an intervention to force Sheldon to face his fear of driving.
Sheldon and the gang are confused when a young grad student is attracted to him.
When Sheldon bans Penny from the apartment for a series of petty infractions, Penny vows to get revenge.
Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.
Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards.
Leonard asks Penny for advice when his new relationship starts moving too fast.
Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.
When Penny's comment about Wolowitz's love life sends him into a depressed stupor, his friends lose their most important teammate in an upcoming fighting-robot competition.
Sheldon develops a scientific procedure for making friends; Kripke controls a new supercomputer.
Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend.
Leonard and Penny are drawn together after a disastrous visit from Leonard's mother (Christine Baranski).
A paintball game leads to a fight between Sheldon and Penny, and romance for Leslie and Wolowitz.
Leonard, Sheldon and Wolowitz are ecstatic to learn that a famous science-fiction actress (Summer Glau) is aboard the train they are taking to San Francisco.
Penny's home business turns into a complete nightmare when Sheldon takes over.
Penny develops a rivalry with a sexy new female neighbor who threatens her position as queen bee of the building.
Wolowitz and Leonard decide to check out a local bar on Ladies' Night.
Koothrappali and Leonard take Wolowitz to Las Vegas; Sheldon is forced to bunk with Penny when he gets locked out of his apartment.
Penny makes a surprising revelation about Leonard while on her date with Stuart; Wolowitz finds a critical design flaw in his NASA project.
While Leonard prepares for a three-month science expedition, he and Penny re-evaluate their feelings for each other.
Getting fired gives Sheldon the opportunity to explore life beyond physics, but when he spends his time weaving ponchos and acting like a shut-in, Leonard calls Sheldon's mother for assistance.