Tom Smallwood, gets laid off from his factory job and makes the decision to follow his dream of becoming a professional bowler.

Bill and Jo juggle a typical day that starts with a parent-teacher conference and ends with a trip to the ER. After defending their parenting style, or lack thereof, to…

A letter prompts Ramona to reconsider her future, and Max tempts fate on the “Troller Coaster.” Steve and DJ have an important talk.

The entire Tanner clan comes together for a final reunion before the family home is sold, but parting turns out to be tougher than expected

Penny squares off with a new beautiful female neighbor who may become the building’s “new Penny.”

A fellow comic book enthusiast’s hitting on Penny leads to Leonard and Howard going to a bar’s Ladies’ Night.

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

Penny’s second date with Stuart sees her making a comment that gives Leonard new hope for a relationship with her. Wolowitz realizes there’s a crucial error in a NASA project…

The guys’ plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.

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.

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.

Sheldon creates a scientific procedure for making friends.

A jealous Leonard reacts to Penny’s new guy by rebounding with Leslie.

Sheldon creates a monster when he introduces Penny to online gaming.

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 numerous minor infractions, she decides to retaliate.

Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.

Penny’s first date with Leonard goes awry; Penny finds Sheldon to be an unwilling confidant.

Penny’s break-up spurs Leonard to summon the courage to ask her out, and each goes to Sheldon for advice on their upcoming date.

The rest of the gang fall for Sheldon’s twin sister, and Leonard’s plan to win her heart is derailed when Sheldon declares he’ll be the one to decide who can…

Penny wants to throw a surprise party for Leonard, but Sheldon’s indulgence at an electronics store throws her off-track.

Leonard volunteers to sign for a package in an attempt to make a good impression on Penny, but when he enlists Sheldon for help, his attempt at chivalry goes terribly…

Leonard asks a woman out after he finds out that Penny is seeing someone.

Sheldon’s getting fired forces him to explore what life has to offer outside physics, leaving Leonard to take drastic action to snap his friend out of his funk.

Penny hosts a Halloween party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills.

With Wolowitz AWOL with one of her friends, Penny’s recruited to fill in for him on the guys’ Halo team

Leonard and Sheldon each lie to avoid seeing Penny’s concert, but Sheldon’s is a bit too complicated for his own good.

With his friends knowing how sour he acts when sick—and avoiding him as a result—Sheldon is nursed by Penny, who hasn’t a clue what she’s in for.

With Sheldon rattled over meeting Dennis, a 15-year-old physicist who’s smarter than he, Leonard helps him look for a way to debunk Dennis’s research.

Sheldon finds himself booted from the gang’s Physics Bowl team and replaced with Leslie, so he forms his own team, hoping to prove he’s superior.

When delivery of another collectible leads to Penny’s lashing out at Leonard, he decides it’s time to give up his habit, much to his friends’ protestation.

Leonard and Sheldon compete for the attention of a famous female physicist.

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

Leonard can only bring one guest on a trip to see CERN’s Large Hadron Collider (the world’s largest and highest energy particle accelerator) in Switzerland on Valentine’s Day.

When the guys find a ring from “The Lord of the Rings” at a garage sale, it threatens to tear them apart.