She began acting in high school, appearing in various musical productions.
She starred in the film The Last Kiss with Zach Braff.
She dated Adam Brody from 2003 to 2006. In 2008, she began dating Star Wars actor Hayden Christensen after meeting him on the set of Jumper. The couple welcomed a daughter named Briar Rose on October 29, 2014. In September 2017, she and Hayden ended their relationship. In 2020, she dated Bill Hader.
She starred in The O.C. with Peter Gallagher.