The gang is concerned when Sheldon’s former admirer, Dr. Ramona Nowitzki, resurfaces while Amy is away at Princeton.

After Leonard, Sheldon and Wolowitz celebrate the completion of the top secret air force project, they are met with an unpleasant surprise. Also, Amy is offered a summer position as…

Leonard isn’t thrilled when Penny considers taking a new job offered by her ex-boyfriend, Zack.

Howard and Bernadette have a hard time leaving Halley in day care when Bernadette returns to work. Also, Bert introduces the gang to his new girlfriend, Rebecca.

Sheldon pushes himself to the limit when he collaborates on projects with Leonard and Wolowitz as well as Amy on the same day. Also, Bernadette is nearing the end of…

Leonard, Penny and Raj adjust to their new living arrangement, and Sheldon takes an interest in Amy’s work.

When Raj moves out of his apartment, Leonard and Penny offer him Sheldon’s old room.

With Koothrappali cut off from his father’s fortune, he appoints Sheldon to help him get out of debt. Also, Penny considers joining Leonard at Comic-Con.

Sheldon beta-tests an MIT invention after hearing it can help him read people’s emotions. Also, Leonard can’t hide his feelings when Penny announces her brother is coming to town, and…

When Bert, a Caltech geologist, wins the MacArthur Genius fellowship, Sheldon is overcome with jealousy. Also, Wolowitz finds an old remote control Stephen Hawking action figure he invented.

After a successful experiment combining their genes, Sheldon will stop at nothing to convince Amy they should procreate. Also, Koothrappali is embarrassed to tell the gang what the new woman…

Leonard and Penny must separate a quarreling Sheldon and Amy when their cohabitation does not go as planned, and Sheldon threatens to break off their relationship when Amy refuses to…

When Amy’s apartment floods, she proposes a “cohabitation experiment” with Sheldon. Also, Howard and Bernadette are upset when Koothrappali learns the gender of the baby before they do.

Tensions rise when the boys struggle to complete their government project on time and Sheldon tries an energy drink to stay awake. Also, Penny and Amy go to a “party”…

Colonel Williams, an Air Force representative from the Department of Material Command sits down to talk with Wolowitz.

After Sheldon’s mother and Leonard’s father share an evening together, everyone deals with an awkward morning the next day. Also, Penny’s family arrives for the wedding ceremony, including her anxiety-ridden…

Chaos ensues when Leonard’s recently divorced parents, Alfred and Beverly, and Sheldon’s devoutly religious mother, Mary, come to town. Also, Wolowitz and Koothrappali think the government is out to get…

Sheldon hires Stuart to spend the day with Amy when he’d rather go to a movie screening. Also, Leonard’s mother, Beverly, comes to town and Penny struggles to make a…

The gang goes to a wine bar and runs into Penny’s old boyfriend, Zack. Also, Bernadette gets stuck spending the evening with Sheldon when she can’t go wine tasting with…

Everyone must choose sides when a small argument between Leonard and Sheldon erupts into a heated fight during a group get-together.

Sheldon spills a secret of Leonard’s when the two take a weekend cabin trip with Penny and Amy. Also, when Koothrappali goes overboard with pregnancy gifts, Wolowitz and Bernadette must…

Meemaw meets Amy, but it isn’t all roses. Meemaw seems to have an axe to grind with her. Sheldon comes to Amy’s defense, but not before Meemaw lets a little…

After having to deal with a sick Sheldon, Leonard, Penny and the gang try to treat themselves to a Sheldon-free weekend.

After more than five years of dating, Sheldon and Amy spend their first night together. Also, Leonard, Wolowitz, and Koothrappali must decide who will take their extra Star Wars movie…

Sheldon has a revelation when he realizes why a song was stuck in his head. Also, Amy invites Dave over for dinner despite their previously awkward date, and Wolowitz and…

Wil Wheaton interviews Sheldon for a Star Trek documentary where he reveals the ring and his plan to propose to Amy. Bernadette wants to start renovating the house and the…

In the midst of a nation-wide helium shortage, Sheldon and Leonard take desperate measures to get the supplies they need. Also, Penny and Bernadette download a dating app on Amy’s…

The guys take a fencing lesson from Barry Kripke and Sheldon finds himself in an awkward position when Kripke expresses interest in Amy. Also, when Stuart struggles to get female…

Sheldon learns of an impending change in his living arrangements and decides to revert back to 2003, a simpler time before he met Leonard and Penny. Also, Howard and Raj…

The guys’ science skills are put to the test when they get a flat tire during Leonard’s bachelor party weekend in Mexico. Also, the girls force Penny to finally tell…

Leonard confronts the woman he kissed on the North Sea in an attempt to set Penny’s mind at ease. Also, Sheldon films a special episode of “Fun with Flags” after…

After driving to Vegas to get married, Penny struggles with Leonard’s confession that he kissed another girl. Also, Sheldon doesn’t know how to act after Amy pushes pause on their…

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…

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…

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…

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…

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…

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…

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…

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.