Sheldon begins a platonic relationship with Amy, Howard reconnects with Bernadette eventually asking her to marry him, Leonard begins to date Raj's sister Priya, Penny becomes friends with Amy and expresses regret at breaking up with Leonard.
S04E01 The Robotic Manipulation
Sep 23, 2010Penny finds herself along for the ride on Sheldon's first date ever; while Wolowitz finds a new use for a robotic arm.
30m
S04E02 The Cruciferous Vegetable Amplification
Sep 30, 2010Sheldon realizes he won't live long enough to download his consciousness into a robot body, and attempts to extend his lifespan.
30m
S04E03 The Zazzy Substitution
Oct 7, 2010The guys are concerned as Sheldon searches for an alternative to human companionship.
30m
S04E04 The Hot Troll Deviation
Oct 14, 2010An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.
30m
S04E05 The Desperation Emanation
Oct 21, 2010Leonard realizes he's the only one without a girlfriend, while Sheldon wants to get rid of his.
30m
S04E06 The Irish Pub Formulation
Oct 28, 2010Leonard keeps an affair secret from Sheldon, Howard and Raj.
30m
S04E07 The Apology Insufficiency
Nov 4, 2010Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.
30m
S04E08 The 21-Second Excitation
Nov 11, 2010While the guys camp in line for a screening, Penny and Bernadette invite Amy to her first slumber party.
30m
S04E09 The Boyfriend Complexity
Nov 18, 2010Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.
30m
S04E10 The Alien Parasite Hypothesis
Dec 9, 2010Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.
30m
S04E11 The Justice League Recombination
Dec 16, 2010The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.
30m
S04E12 The Bus Pants Utilization
Jan 6, 2011Leonard's idea for a smartphone app derails his friendship with Sheldon.
30m
S04E13 The Love Car Displacement
Jan 20, 2011Tension runs high when everyone is staying at the same hotel for a science event and Bernadette runs into her ex-boyfriend.
30m
S04E14 The Thespian Catalyst
Feb 3, 2011Sheldon hopes acting lessons from Penny will help him become a better teacher. Meanwhile, Koothrappali fantasizes about his best friend's girlfriend.
30m
S04E15 The Benefactor Factor
Feb 10, 2011A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.
30m
S04E16 The Cohabitation Formulation
Feb 17, 2011As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.
30m
S04E17 The Toast Derivation
Feb 24, 2011Sheldon struggles to cope when he realizes it's actually Leonard who is the center of their social group.
30m
S04E18 The Prestidigitation Approximation
Mar 10, 2011Leonard must choose between new girlfriend Priya and his friendship with Penny. Meanwhile, Howard drives Sheldon crazy with a magic trick.
30m
S04E19 The Zarnecki Incursion
Mar 31, 2011When someone hacks Sheldon's online game account, the guys go on a quest to find the culprit.
30m
S04E20 The Herb Garden Germination
Apr 7, 2011Sheldon and Amy experiment on their friends by spreading gossip, while Howard takes a big step in his relationship with Bernadette.
30m
S04E21 The Agreement Dissection
Apr 28, 2011When Priya uses her lawyer skills to pick apart the roommate agreement, the girls take Sheldon dancing.
30m
S04E22 The Wildebeest Implementation
May 5, 2011Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.
30m
S04E23 The Engagement Reaction
May 12, 2011When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.
30m
S04E24 The Roommate Transmogrification
May 19, 2011When Bernadette receives her Ph.D., the guys take joy in reminding an emasculated Wolowitz that he is the only one in their group who isn't a doctor. Meanwhile, Koothrappali becomes Sheldon's new roommate after hearing Leonard and Priya engaging in a "Star Trek" bedroom fantasy.
30m
