Missy asks some uncomfortable questions at church, and Connie and Georgie go into business together.

Sheldon tries to convince Dr. Sturgis to return to the university. Also, Georgie upsets the family when he makes a life-changing decision.

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

When Leonard and Penny aren’t speaking, Sheldon goes to extremes to keep them both happy.

Leonard must face his fears after being contacted by his high school tormentor.

Penny is horrified when Amy gives her a gift: a huge, quite horrible painting of the two of them. With no good way to avoid displaying it, she only hangs…

When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she’s regrets.

Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.

Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.

When Amy gets sick, Sheldon tries to nurse her back to health; Wolowitz and his father-in-law plan a fishing trip.

During a game, Sheldon revisits Christmas memories; Amy, Penny and Bernadette look for a date for Koothrappali.

When Sheldon is accused of sexual harassment, he ends up getting Raj, Leonard and Wolowitz in trouble.

Howard considers whether or not he should open a letter from his father; Penny and Leonard host a “grown-up” cocktail party.

Leonard and Sheldon hire the host (Bob Newhart) of their favorite childhood TV show to perform; Bernadette and Howard run into trouble while dog-sitting for Raj’s pet.

Amy and Sheldon’s relationship takes a surprising turn during a game of “Dungeons & Dragons”; Lucy and Koothrappali have an awkward date.

Bernadette tries to negotiate peace between Sheldon and Wolowitz; Penny receives an embarrassing offer; Raj wants Amy to write to a woman on his behalf.

While Raj is wracked with guilt when he tries to date two women at once, Penny wrestles with whether to take a role in a cheesy movie and Sheldon is…

As the gang celebrates Star Wars Day, Sheldon discovers he is having difficulty dealing with the death of Professor Proton.

When Raj is asked to create a message in case a NASA mission discovers alien life, the guys fight over what he should do. Also, Penny is torn between auditioning…

Wolowitz questions his engineering abilities when he and Sheldon can’t get a toy drone to fly. Meanwhile, a cancelled flight nearly prevents Leonard from giving the commencement address at his…

Personalities collide when Sheldon and Leonard’s mothers finally meet. Meanwhile, Howard finally decides to “man up” and do his fair share of the housework – but not without a little…

Sheldon pushes Leonard and Penny to choose a date for their wedding and deals with dramatic changes in his own relationship with Amy.

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.

When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Also, Wolowitz meets the half-brother he never knew he had, and when Penny is…

During their weekend in Las Vegas, Bernadette and Amy accuse Penny of being a buzz kill. The guys try to invent the next big thing.

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. Leonard and Penny seek…

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 the gang recreates a high-school prom night on the roof of the guys’; apartment building, Sheldon feels pressure to participate in all the typical romantic traditions.

When Leonard gets minor surgery on his nose, Sheldon is the one in need of sympathy. Meanwhile, Raj’s parents’ impending divorce causes Howard and Bernadette to work on their own…

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 is…

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…

Wolowitz 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.

The gang tries to help Sheldon when he becomes stuck in a rut at work by increasing his anxiety level. Howard teases Raj with a new game called “Cinnamon or…

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.

Wolowitz receives some shocking news as everyone prepares for the reopening of Stuart’s comic book store. Penny teaches Sheldon how to “let it go,” but can’t follow her own advice…

As a joke, Sheldon and Penny try an experiment designed to make participants fall in love. Also, Leonard, Amy, Raj and Emily spend the evening trying to escape a room…

Trouble arises when Amy learns Sheldon has applied for a one-way mission to colonize Mars. Also, a trip to the pet store ends in a fight for Sheldon and Amy,…

Friction ensues when a magazine fails to mention Leonard in an article about the paper he co-wrote with Sheldon. Also, a blackout at Mrs. Wolowitz’s home leads to a final…

When Leonard and Sheldon are invited to speak at UC Berkeley, they take a detour to try to meet an idol. Also, when Bernadette and Howard battle over the fate…

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.