Episode 1 / The Proposal Proposal

In the eleventh season premiere, Amy gives Sheldon an answer to his proposal, while Howard and Bernadette struggle with some unexpected news. LAURIE METCALF returns as Sheldon's mother, Mary; RIKI LINDHOME returns as Ramona; and STEPHEN HAWKING returns as Himself.

Episode 2 / The Retraction Reaction

Leonard angers the university — and the entire physics community — after he gives an embarrassing interview. Also, Amy and Bernadete bond over having to hide their success from Sheldon and Howard. NPR Host IRA FLATOW returns as himself, and REGINA KING returns as Mrs. Davis.

Episode 3 / The Relaxation Integration

As Sheldon stresses out about picking a wedding date, Amy tries to convince him that he has a more laid-back side by recording him talking in his sleep. Meanwhile Raj and Stuart (series regular KEVIN SUSSMAN) compete to win the heart of Bernadette's new coworker, Ruchi (guest star SWATI KAPILA).

Episode 4 / The Explosion Implosion

Howard and Sheldon bond over their relationships with their disappointing fathers when they drive to the desert to shoot off a model rocket. Meanwhile, it rubs Leonard the wrong way when his mom (CHRISTINE BARANSKI) finds a new best friend in Penny.

Episode 5 / The Collaboration Contamination

Raj and Sheldon confide in Bernadette when they can't handle Amy working together with Howard. Meanwhile, Leonard and Penny learn new tactics for dealing with Sheldon from an unlikely source.

Episode 6 / TheEpisodeTitle

Sheldon goes head-to-head with WIL WHEATON (recurring as Himself) for the role of the new Professor Proton; Meanwhile, Penny steps in to take care of Halley when Bernadette and Howard both wind up on bed rest.

Episode 7 / The Geology Methodology

Sheldon and Bert collaborate on a research project, despite Sheldon's embarrassment. Meanwhile, Penny and Bernadette coach Raj on how to navigate his relationship with Ruchi.

Episode 8 / The Tesla Recoil

Leonard and Howard are furious when they learn that Sheldon went to work with the military behind their backs. While Bernadette is on bed rest, she asks Raj go investigate when she suspects Ruchi might be trying to steal her job. Guest star DEAN NORRIS returns as Colonel Williams.

Episode 9 / The Bitcoin Entanglement

Sheldon tries to teach the guys a lesson after they cut him out of a potentially valuable Bitcoin investment; A seven-year-old video reveals a secret about Leonard and Penny's relationship.

Episode 10 / The Confidence Erosion

Sheldon and Amy try to eliminate stress from wedding planning by applying math to the process. Also, Raj "breaks up" with Howard after realizing his best friend is actually hurting his confidence.

Episode 11 / The Celebration Reverberation

Sheldon and Howard plan birthday celebrations for Amy and Halley, respectively. Leonard receives a Christmas letter from his brother that causes him to spiral out about his own lack of accomplishments.

Episode 12 / The Matrimonial Metric

To discover who would be most qualified to be Best Man and Maid of Honor at their wedding, Sheldon and Amy subject their friends to a series of secret experiments; Penny reveals her true feelings about Amy.

Episode 13 / The Solo Oscillation

When Sheldon kicks Amy out to work solo, she and Leonard bond during a series of science experiments. Meanwhile, Bert, the geologist, replaces Howard in his band, "Footprints on the Moon," and Sheldon finds Penny a surprising source of scientific inspiration.

Episode 14 / The Separation Triangulation

Raj finds himself in the middle of a domestic drama when he learns the woman he's dating, Nell (guest star BETH BEHRS), has a very upset husband, Oliver (guest star WALTON GOGGINS). Also, when Sheldon rents his old room back for a quiet place to work, he drives Leonard crazy by being a model tenant.

Episode 15 / The Novelization Correlation

When Sheldon petitions Wil Wheaton to appear on the new Professor Proton show, Wil offers a role to Amy instead; Penny gets angry when she thinks the female protagonist in Leonard's novel is based on her.

Episode 16 / The Neonatal Nomenclature

When Bernadette won't go into labor, all her friends try different tactics to get things started; and Howard confronts Bernadette after Amy accidentally reveals that she's already chosen their son's name.

Episode 17 / The Athenaeum Allocation

While Leonard jumps through hoops to help secure the perfect wedding venue for Sheldon and Amy, Howard and Bernadette have a difficult time deciding which one of them should stay at home with the kids and who should return to work.

Episode 18 / The Gates Excitation

When Penny gets the opportunity to host BILL GATES (guest starring as himself) at work when his company wants to partner with her pharmaceutical company, Leonard, Howard and Raj do everything in their power to meet him, while Sheldon thinks he's the victim of an April Fool's prank.

Episode 19 / The Tenant Disassociation

When Leonard learns Sheldon is the president of the Tenants Association, he decides to run against him; Bernadette encourages Howard and Raj to find the owner of a drone after they find it in the backyard.

Episode 20 / The Reclusive Potential

A brilliant, but reclusive scientist, Doctor Wolcott (guest star PETER MacNICOL) invites Sheldon to his cabin in the middle of nowhere, and Leonard, Howard and Raj go along for the trip. Penny and Bernadette improvise when Amy doesn't like the tame bachelorette party they planned for her.

Episode 21 / The Comet Polarization

Sheldon's comic book store experience changes when writer NEIL GAIMAN (Coraline, American Gods) puts Stuart's store on the map. And friendships are threatened when Raj takes credit for Penny's astronomical discovery.

Episode 22 / The Monetary Insufficiency

Sheldon goes to Vegas and does everything he can to win three hundred million dollars for science. Meanwhile, Penny and Bernadette take Amy shopping for wedding dresses, but her terribly choice entangles them in a web of lies.

Episode 23 / The Sibling Realignment

When Sheldon learns that his mother won't attend his wedding unless he invites his older brother, Georgie, he and Leonard travel to Texas to end a family feud. Meanwhile, the Wolowitz kids inadvertently infest Amy, Bernadette, Howard and Raj with pinkeye.

Episode 24 / The Bow Tie Asymmetry

On the eleventh season finale, Amy's parents (guest stars KATHY BATES and TELLER) arrive along with Sheldon's family (guest stars LAURIE METCALF, JERRY O'CONNELL and COURTNEY HENGGELER). And everybody's focused on making sure all goes according to plan — everyone except the bride and groom. MARK HAMILL and WIL WHEATON also guest star.