Episode Guide :: Season 4
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401
The Robotic ManipulationSeptember 23, 2010
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402
The Cruciferous Vegetable AmplificationSeptember 30, 2010
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403
The Zazzy SubstitutionOctober 7, 2010
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404
The Hot Troll DeviationOctober 14, 2010
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405
The Desperation EmanationOctober 21, 2010
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406
The Irish Pub FormulationOctober 28, 2010
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407
The Apology InsufficiencyNovember 4, 2010
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408
The 21-Second ExcitationNovember 11, 2010
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409
The Boyfriend ComplexityNovember 18, 2010
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410
The Alien Parasite HypothesisDecember 9, 2010
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411
The Justice League RecombinationDecember 16, 2010
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412
The Bus Pants UtilizationJanuary 6, 2011
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413
The Love Car DisplacementJanuary 20, 2011
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414
The Thespian CatalystFebruary 3, 2011
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415
The Benefactor FactorFebruary 10, 2011
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416
The Cohabitation FormulationFebruary 17, 2011
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417
The Toast DerivationFebruary 24, 2011
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418
The Prestidigitation ApproximationMarch 10, 2011
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419
The Zarnecki IncursionMarch 31, 2011
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420
The Herb Garden GerminationApril 7, 2011
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421
The Agreement DissectionApril 28, 2011
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422
The Wildebeest ImplementationMay 5, 2011
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423
The Engagement ReactionMay 12, 2011
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424
The Roommate TransmogrificationMay 19, 2011

Available now
Relive the complete fourth season of The Big Bang Theory again with this three-disc DVD box-set. Featuring all twenty-four episodes of the show's fourth season along with never-before-seen bonus features.

Also available on Blu-ray
Season Recap
The Big Bang Theory's fourth season focuses on character growth as Sheldon enters a platonic relationship with Amy, Howard restarts his romance with Bernadette, and Leonard starts a serious relationship with Raj's sister Priya.
As Sheldon becomes comfortable spending more time with Amy, his "girl who is a friend but not a girlfriend", starts to spend more time with the group and forms friendship with Penny. Howard's girlfriend Bernadette also becomes a part of the group. After dating for a few months, Howard and Bernadette get engaged after he proposes.
Leonard enters a long-term relationship with Priya, Raj's sister, after she moves to Pasadena. Seeing Leonard with another women, Penny begins to regret breaking up with him. In the season finale, after a night of drinking, Raj and Penny get very close.
The Big Bang Theory's fourth season contained twenty-four episodes aired between September 23, 2010 and May 19, 2011. For its fourth season, The Big Bang Theory moved to Thursdays at 8:00 on CBS, to form a new comedy block. Although the show continued to perform well in the ratings, it fell somewhat from the third season. The new timeslot lacked the strong lead-in the show had on Mondays, with TV's then-#1 sitcom Two and a Half Men, and suffered fewer people watching TV at the earlier time. Kaley Cuoco was absent from two episodes during the season, due to a broken leg from a horseback-riding accident.