The fourth season of the American television sitcom The Big Bang Theory aired on CBS from September 23, 2010 to May 19, 2011. Melissa Rauch and Mayim Bialik auditioned and were promoted to the main cast during this season as Dr. Bernadette Rostenkowski and Dr. Amy Farrah Fowler respectively. Johnny Galecki received a nomination for the Primetime Emmy Award for Outstanding Lead Actor in a Comedy Series at the 63rd Primetime Emmy Awards for the episode "The Benefactor Factor". Jim Parsons won the same award for the episode "The Agreement Dissection".

Production

During the season, Kaley Cuoco's character Penny was absent from episodes 5 and 6 after Kaley fell off a horse and broke her leg. When returning to the series, she was shown working as a bartender instead of waitressing at her usual workplace, The Cheesecake Factory, to hide her injury.

Cast

Main cast

Special guest cast

Recurring cast

Guest cast

Episodes

Ratings

Reception

The fourth season received particular praise for character developments. Alan Sepinwall of Uproxx praised the additions of Bernadette and Amy to the cast, writing that "With Amy Farrah Fowler and Bernadette promoted to semi-permanent status, the show is now able to spend large chunks of each episode focusing only on the women, and in the process has made Penny a much more well-rounded character rather than just a foil for the nerds". Emily VanDerWerff of The A.V. Club wrote that "Jim Parsons and Kaley Cuoco's interplay remains the show's secret weapon", and Eric Hochberger of TV Fanatic wrote: "Really though, everything about the main story worked amazing. Mayim fits in perfectly in The Big Bang Theory cast and played off of Kaley Cuoco just as well as Emmy Award-winning Parsons".