Christensen had several small roles in various television programs before starting her movie career. These shows include The Geena Davis Show, Frasier, The Practice, 3rd Rock from the Sun, and Touched by an Angel. She was named one of People magazine's "Breakthrough Stars of 2001." For her performance in Traffic she received the awards for Female Breakthrough Performance at the MTV Movie Awards, Female Standout Performance at the Young Hollywood Awards, and Outstanding Performance by a Cast Ensemble at the Screen Actors Guild Awards. In 2005, she briefly went into music as she recorded a version of Let's Fall In Love with John Stevens for his debut album Red. In 2006, she starred in the series Six Degrees, which debuted on the ABC fall schedule in 2006 but low ratings caused its cancellation after one season. She made a cameo in the Joaquin Phoenix directed video "Tired of Being Sorry" for Balthazar Getty's band Ringside. She is part of the cast of the fiim adaptation of Veronika De