Born in rural southern Illinois, Karen spent her first 10 years traveling around the country with her mother, her FBI agent father, and two sisters. At 17, after graduating from high school, Karen moved to New York to study art and design. She later attended the University of Maryland and spent time traveling through South and Central America. In 1974 Karen joined a theatre group and 3 years later moved back to New York and studied with the Lee Strasberg Institute. In 1978, she made her major film debut in National Lampoon's Animal House (1978) and Hollywood took notice. Her next big break came in Raiders of the Lost Ark (1981) where she created the role of "Marion Ravenwood". Karen also debuted on Broadway in 1982 in "Monday After the Miracle, The". After a few small films, including the underrated Until September (1984), directed by Richard Marquand, and other stage appearances, she made the successful science fiction movie Starman (1984). After that her movie career waned as she preferred to work on the stage. She married Kale Browne in 1988 and had Nicholas, her first child in 1990. Since the birth of Nicholas, Karen has done smaller film roles and TV movies to concentrate on raising Nicholas.