Accidentally on Purpose is an American television sitcom created by Claudia Lonow, that aired on CBS from September 21, 2009, to April 21, 2010, during the 2009–10 season.

[1] The series stars Jenna Elfman, Jon Foster, Ashley Jensen, Nicolas Wright, Grant Show, and Lennon Parham and was produced by BermanBraun and CBS Television Studios.

While Billie receives encouragement and advice from her alcoholic best friend Olivia (Ashley Jensen) and her conventional, younger, married sister Abby (Lennon Parham), she also has to deal with Zack's freeloading friend Davis (Nicolas Wright), among others, when they start turning her place into a frat house, leaving Billie to question whether she is living with a boyfriend, a roommate, or a second child to raise.

[3] The theme song for the show is "Birds of a Feather", written by David Fagin of the indie-rock band The Rosenbergs.

[6] In early 2010 CBS moved Accidentally on Purpose to Wednesday nights from Mondays, to accommodate the midseason return of Rules of Engagement and the cancellation of Gary Unmarried.