Joanna Crussie DeVarona Kerns is an American actress and director best known for her role as Maggie Seaver on the family situation comedy Growing Pains from 1985 to 1992.

After Growing Pains ended, she turned to directing. She directed one episode of Growing Pains while starring on the show and got hooked. She has also directed episodes of television shows including Dawson's Creek, Titans, Scrubs, Private Practice, Psych, Felicity, Grey's Anatomy, Privileged, ER, Ghost Whisperer, Army Wives, Pretty Little Liars, Switched at Birth, The Goldbergs, This Is Us, and Fuller House.

She has also made notable appearances in feature films, including APE, Girl, Interrupted, and the 2007 comedy Knocked Up. She has also starred in a number of TV movies.

In 1974, Kerns met a commercial producer, Richard Kerns, on the set of a commercial, and they married two years later. Their marriage lasted nine years and the couple had a daughter, Ashley Cooper. In 1994, she married Marc Appleton, a prominent Los Angeles architect. In August 2019, she filed for divorce from Appleton.

She previously dated comedian and actor Freddie Prinze a short time before he died of a self-inflicted gunshot wound. The two had worked together on the 1976 TV movie, The Million Dollar Rip-Off.