Written by Oscar-winning filmmaker Paul Haggis and due in theaters Friday, the relationship comedy/drama is about a young architect (Braff) who feels the world closing in on him when his girlfriend (Jacinda Barrett) announces she is pregnant.
Bilson, star of the hit U.S. television series, "The O.C.," plays the college student/temptress who complicates matters.
Describing herself as a fan of "Garden State," the quirky 2004 film the "Scrubs" star wrote, directed and starred in, Bilson told reporters in New York she was disappointed when an earlier opportunity to collaborate with Braff on a music video didn't work out.
"So, when I found out he was attached to this film, I was just, like, full steam ahead to try to do everything I could to get the part," explained the 25-year-old actress. "You can only hope that you have chemistry and it works out in the auditioning room, but it did."