Episode 1 / The Conjugal Conjecture

In the tenth season premiere, Penny's family arrives for the wedding ceremony, including her anxiety-ridden mother, Susan (guest star KATEY SAGAL), her drug-dealing brother, Randall (guest star JACK McBRAYER) and her father Wyatt (returning guest star KEITH CARRADINE). After Sheldon's mother, Mary (recurring guest star LAURIE METCALF) and Leonard's father, Alfred (returning guest star JUDD HIRSCH) share an evening together, however, everyone deals with an awkward morning the next day. Recurring guest star CHRISTINE BARANSKI returns as Leonard's mother, Dr. Beverly Hofstadter, while Breaking Bad's DEAN NORRIS guest stars as Air Force Representative Colonel Williams.

Episode 2 / The Military Miniaturization

Colonel Williams, an Air Force representative from the Department of Material Command, sits down for a talk with Howard.

Episode 3 / The Dependence Transcendence

Tensions rise when the guys 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" at the house of Bert, the geologist (guest star BRIAN POSEHN). And Raj learns Bernadette's true feelings about her pregnancy when they clean out the future baby room. Dean Norris returns as Air Force Colonel Williams.

Episode 4 / The Cohabitation Experimentation

When Amy's apartment floods, she proposes a "cohabitation experiment" with Sheldon. Meanwhile, Howard and Bernadette are upset when Raj learns the gender of their baby before they do.

Episode 5 / The Hot Tub Contamination

Leonard and Penny must separate a quarreling Sheldon and Amy, when their cohabitation experiment doesn't go as planned. Sheldon threatens to break off their relationship when Amy refuses to adhere to the "bathroom schedule." Also, Howard and Bernadette find unexpected guests at their house when they decide to stay home from a planned vacation.

Episode 6 / The Fetal Kick Catalyst

Penny is surprised to learn she has fans of her performance in "Serial Ape-ist" when she attends the Van Nuys Comic-Con with Leonard. Also, Amy hosts a Sheldon-style brunch at Penny's apartment. And Howard makes an impulsive purchase when he starts stressing out about the baby on the way.

Episode 7 / The Veracity Elasticity

In order to continue living with Sheldon, Amy lies to him about repairs being made to her apartment; and they host an "on location" episode of "Fun with Flags" in Penny's apartment. Also, Leonard lets Penny decorate Sheldon's old room after he learns that she has secretly been moving Leonard's collectibles into storage.

Episode 8 / The Brain Bowl Incubation

After a successful experiment combining their genes, Sheldon will stop at nothing to convince Amy they should procreate. Also, Raj is embarrassed to tell the gang what the new woman he's dating does for a living.

Episode 9 / The Geology Elevation

When CalTech geologist Bert (recurring guest star BRIAN POSEHN) wins the MacArthur Genius Fellowship, Sheldon is overcome with jealousy. Meanwhile, Howard finds an old remote control Stephen Hawking action figure he invented. STEPHEN HAWKING returns to guest star as himself.

Episode 10 / The Property Division Collision

A battle ensues when Leonard and Sheldon argue over who will get custody of their shared belongings. Also, Raj and Stuart fight to be the most helpful during Bernadette's final weeks of pregnancy. CHRISTOPHER LLOYD guest stars as Theodore.

Episode 11 / The Birthday Synchronicity

While Sheldon and Amy celebrate Amy's birthday, Howard and Bernadette welcome their new Baby Wolowitz.

Episode 12 / The Holiday Summation

Sheldon and Amy visit Leonard and Penny for the first time since the holidays and share details about their terrible trip to Texas when his feelings were hurt while visiting his Mom. Meanwhile, Howard and Bernadette struggle with the challenges of a newborn, and Leonard & Penny's attempt at a new tradition leads to disaster. Laurie Metcalf returns as Sheldon's mother, Mary.

Episode 13 / The Romance Recalibration

After Penny feels that Leonard is taking her for granted, she decides to go on a spa weekend with Amy, leaving Sheldon to play the unlikely peacemaker. Meanwhile, Howard and Raj try to fix a squeaky floorboard in the baby's room.

Episode 14 / The Emotion Detection Automation

Sheldon beta tests an MIT invention that helps him read people's emotions. Meanwhile, Raj invites his ex-girlfriends over to give him dating advice, and Leonard can't hide his feelings when Penny announces that her brother is coming to town. Guest stars LAURA SPENCER, KATE MICUCCI, ALESSANDRA TORRESANI and KATIE LeCLERC return as Raj's ex-girlfriends.

Episode 15 / The Locomotion Reverberation

Leonard and Howard try to distract Sheldon with tickets to a historic railway when he slows the progress of their guidance system. Meanwhile, Penny and Amy take Bernadette out for the night, leaving Raj and Stuart to care for baby Halley. Dean Norris returns as Colonel Williams.

Episode 16 / The Allowance Evaporation

Sheldon and Amy have their first fight since moving in together, after he shares intimate details of their relationship with people at the university. Meanwhile, Raj is shocked by the realities of financial independence when he stops receiving support from his father (guest star BRIAN GEORGE).

Episode 17 / The Comic-Con Conundrum

When Raj is cut off from his father's fortune, he appoints Sheldon in charge of his finances to help him get out of debt. Also, Penny considers joining Leonard at Comic-Con.

Episode 18 / The Escape Hatch Identification

When Raj moves out of his apartment, Leonard and Penny offer him Sheldon's old room. Christine Baranski returns as Leonard's mother, Beverly.

Episode 19 / The Collaboration Fluctuation

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

Episode 20 / The Recollection Dissipation

Sheldon pushes himself to the limit when he collaborates on projects with Leonard and Howard as well as Amy on the same day. Also, Bernadette nears the end of her maternity leave and must return to work. JOEL MURRAY guest stars as Doug.

Episode 21 / The Separation Agitation

Howard and Bernadette have a hard time leaving Halley in daycare when Bernadette returns to work. Also, Bert introduces the gang to his new girlfriend, Rebecca (guest star APRIL BOWLBY).

Episode 22 / The Cognition Regeneration

Leonard isn't thrilled when Penny considers taking a new job offered by her ex-boyfriend, Zack (guest star BRIAN THOMAS SMITH).

Episode 23 / The Gyroscopic Collapse

After Leonard, Sheldon and Howard celebrate the completion of their top secret Air Force project, they're met with an unpleasant surprise. Also, Amy is offered a summer position as a visiting researcher.

Episode 24 / The Long Distance Dissonance

On the tenth season finale, the gang is concerned when Sheldon's former admirer, Dr. Ramona Nowitzki (returning guest star RIKI LINDHOME) resurfaces while Amy is away at Princeton.