A San Francisco newspaper film critic becomes pregnant after a hookup with a much younger man and together they raise a non-traditional family. Golden Globe Award winner Jenna Elfman (Dharma & Greg) plays Billie, who after a hard breakup with her boss, James (Melrose Place's Grant Show) then gets knocked up by Zack (Windfall's Jon Foster). They agree on an unconventional arrangement to raise the child and live together platonically. But when Zack's friends turn her place into a frat house, Billie isn't sure that the plan can work out. Completing the cast are Ashley Jensen (Ugly Betty) as Billie's best friend Olivia, Lennon Parham as her younger married sister Abby, and Nicolas Wright as Davis, one of Zack's freeloading friends. Based on the bestselling novel of the same name by Mary F. Pols, Accidentally on Purpose is executive-produced by Lloyd Braun, Gail Berman, Gene Stein, and Claudia Lonow with CBS Television Studios.