The girls decide to re-enact their high school proms with the guys. While Sheldon feels under pressure to commit to his relationship with Amy, Howard worries about who Stuart will…

Sheldon faces a personal crisis after deciding he’s wasting his time with string theory. Meanwhile, a double date between Raj, Emily and the Wolowitzes ends in embarrassment for Howard.

While Sheldon says a tearful goodbye to the final installment of “Fun with Flags”, Leonard, Howard and Raj search for something significant in a dead professor’s research. And Bernadette finds…

To prepare for a date with Emily, Howard acclimates Raj to horror movies. Penny and Sheldon are upset when they discover Amy and Bernadette lied to avoid hanging out with…

Leonard and Howard turn to Raj for help in dealing with a work emergency when they nearly come to blows after blaming each other for a potential disaster at the…

As the gang celebrates Star Wars Day, Sheldon has difficulty dealing with the recent death of Arthur “Professor Proton” Jeffries.

Howard tries to distract Raj, who is anxiously awaiting data from a space probe he helped launch. Meanwhile, Sheldon and Leonard go dress shopping with Penny and Amy.

When Sheldon becomes stuck in a rut with his work, the gang tries to help him by raising his stress levels. Howard teases Raj with a game called “Emily or…

After the guys can’t get Comic-Con tickets, Sheldon tries to hold his own convention and winds up spending a wild night with James Earl Jones. Meanwhile, the girls try to…

Sheldon get upset about his career, the destruction of the comic book store and Leonard and Penny’s future living arrangements. Howard and Bernadette can’t keep hold of a caretaker for…

Raj’s honesty comes back to haunt him when his new girlfriend is unfriendly to Penny. The guys think about becoming part owners in Stuart’s store.

Leonard and Sheldon publish a paper which is widely accepted except for comments from an internet troll. Meanwhile, the girls reminisce about embarrassing incidents from their past.

Sheldon and Amy take a train ride to Napa Valley with Howard and Bernadette on Valentine’s Day. Leonard and Penny take Raj’s dog to the vet when she accidentally eats…

The girls head to Las Vegas for some weekend fun, while the guys try to invent something cool, but only come up with new ways to procrastinate.

Sheldon and Raj test whether they could survive a dark-matter research expedition in a salt mine by simulating the conditions in a steam tunnel deep underground. Meanwhile, Leonard and Penny…

After arguing with Sheldon, Howard tries to make amends by taking him to NASA headquarters in Houston. Penny has second thoughts about quitting her waitressing job when her car dies….

The guys try to help Penny out of an awkward work dilemma, when a smitten doctor shows up at her door after her flirtatious sales techniques work a little too…

When a mistake comes to light, Sheldon makes Leonard walk a mile in his shoes; Penny decides to confront Raj’s ex-girlfriend, Lucy.

Sheldon protests when the gang drags him to Mrs. Wolowitz’s house for Thanksgiving. Meanwhile, Penny and Leonard must deal with a mistake from her past.

Leonard has to deal with the fallout of disproving Sheldon’s new scientific discovery. Raj spends a week at Howard and Bernadette’s apartment.

Leonard and Amy make an unexpected trip to Arizona to fetch Sheldon; Penny interviews for a job at Bernadette’s company; Stuart’s relationship with Mrs. Wolowitz disturbs Howard.

While Sheldon is at home in Texas, the rest of the gang realizes how much he has changed their lives as they decorate the apartment Christmas tree.

Sheldon is forced to teach a class as a Junior Professor and Howard decides to enroll in it. Meanwhile, Amy plays both sides when tension arises between Penny and Bernadette.

When Penny’s big acting break on NCIS is a bust, Leonard struggles to help her, which results in Penny asking Leonard a bold relationship question. Meanwhile, Raj and Stuart try…

Sheldon tries to relax after he is forced to take a vacation. Meanwhile, Leonard struggles to be supportive of Penny after she quits her job, and Bernadette seeks Stuart’s help…

Wolowitz feels nervous when he is asked to throw the first pitch at a Los Angeles Angels game. Penny and Leonard want to prove Sheldon wrong after he says he…

With Leonard away, Sheldon and Penny spend quality time together sharing intimate secrets. Also, Wolowitz helps Raj get over his ex-girlfriend.

Leonard and Sheldon’s friendship is tested; Howard’s latest foray into helping his mother has some disastrous side effects.

When the entire gang competes in a scavenger hunt designed by Raj, it brings out the best – and worst – in everyone.

Sheldon gets mad at Amy for ruining one of his favorite movies, Raj and Stuart try to make their online dating profiles more appealing, and Leonard tries to play the…

Amy starts working at Caltech which causes friction with Sheldon. Howard agrees with Sheldon who mentions this to Bernadette causing a big fight for the Wolowitzes.

Sheldon’s latest scientific breakthrough leaves him feeling like a fraud; a romantic gesture between Howard and Bernadette causes Penny to up her game with Leonard.

Sheldon seeks payback when Arthur “Professor Proton” Jeffries asks Leonard for help on a project instead of him. Raj gets upset at Howard for crashing his night with the girls.

Sheldon must choose between joining Amy at her aunt’s birthday party or playing videogames all weekend with the guys.

Penny buys Leonard and Sheldon “Star Trek” collectibles as a thank-you, leading Sheldon to be haunted by Mr. Spock. Meanwhile, Raj decides he has met the “Future Mrs. Koothrappali” after…

When Wolowitz gets to work with Stephen Hawking, Sheldon is willing to do anything to meet his hero.

When NASA moves up Howard’s mission, he must face his fears and Bernadette’s dad, thus putting the wedding plans in jeopardy. Meanwhile, Leonard says something surprising to Penny in the…

The fifth season ends with Howard and Bernadette deciding to get married before his NASA mission, causing the gang to scurry into overdrive in an effort to stage the wedding….

Sheldon’s selfish demands force Leonard to reconsider their friendship. Meanwhile, Wolowitz tries to pick his astronaut nickname.

When Sheldon is forced to take his vacation, he goes to work with Amy in her neurobiology lab.