"American Idol" host Ryan Seacrest announced on his radio show Monday that the reality competition will be adding a fourth judge this season  -- Grammy-nominated songwriter Kara DioGuardi.

DioGuardi has written songs for Celine Dion, Christina Aguilera, Gwen Stefani, Britney Spears, Miley Cyrus, Pussycat Dolls, The Jonas Brothers, Jessica Simpson, Santana, Pink and much more.

Up until the last season, the show had three judges: Randy Jackson, Paula Abdul and Simon Cowell. "Idol" comes back for its eighth season on January 2009.