When Howard finally breaks the news to his mom that he’s engaged to Bernadette, it lands her in the hospital.

Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas, and Sheldon becomes locked out of his apartment and must stay with Penny.

Sheldon and Amy decide to start several rumors about the others as a test. Meanwhile, Howard takes his relationship with Bernadette to even higher level.

Leonard tells Penny about how he met Sheldon for the first time…and what happened to the elevator.

A date between Raj and Lucy takes both of them out of their comfort zones. After a trip to Las Vegas goes awry, the girls join in on a Dungeons…

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…

Penny’s home business turns into a complete nightmare when Sheldon takes over.

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.

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…

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

Sheldon becomes concerned when everybody begins to hang out at Raj’s apartment and discovers Leonard is the center of the group.

A bad day causes Penny to reevaluate her life choices – including Leonard. Meanwhile, Howard and Bernadette struggle to care for Mrs. Wolowitz, and Raj gets relationship advice from Sheldon.

The girls get involved when Leonard, Sheldon and Raj compete for tenure at the University.

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

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

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

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 Penny are drawn together after a disastrous visit from Leonard’s mother.

Sheldon winds up in traffic court when he gets a ticket because of Penny.

Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about a friend’s girlfriend.

Leonard, Sheldon and Howard give lectures on science to junior high students. The girls ditch work to go to Disneyland. Raj devises a date for Lucy that fixes their social…

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.

Sheldon battles Kripke for a coveted office at the university. Penny receives a very unusual gift from Amy.

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…

The guys search for a perfect Valentine’s Day gift for their significant others; Stuart and Raj host a “lonely people” party at the comic book store.

Penny’s criticism of Wolowitz’s romantic life pushes him into depression and AWOL for a fighting robot battle the rest of guys are depending on him for.

When Sheldon visits his Mom in Houston, he is forced to confront a new reality. Meanwhile, Raj’s ‘Murder Mystery’ party starts some fights within the gang.

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

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 find a “super” use for Penny’s new boyfriend, Zack, when they enter a costume contest as the Justice League.

When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.

Leonard buys a dining room table and it causes Sheldon to reevaluate the changes in his life. Meanwhile, Wolowitz is offered a chance to go back to space and Bernadette…

Sheldon faces a crisis of confidence when he is forced to work with his nemesis, Barry Kripke; Raj and Howard buy expensive action figures of themselves.

Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon’s stringent standards.

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…

Leonard, who broke up with Priya, asks Penny out to a spur-of the-moment romantic dinner for two, and the duo contemplates on their relationship.

While the guys camp in line for a long-awaited movie screening, Penny and Bernadette invite Amy to her first slumber party.

Penny gets help from Sheldon in order to understand what Leonard’s work is, while Wolowitz develops a jealousy when Leonard starts hanging out with his new girlfriend.

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…

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