Karen Jane Allen was born in Carrollton, a rural town in southern Illinois, to Patricia (Howell),a teacher, and Carroll Thompson Allen, an FBI agent. She spent her early years traveling around the country with her parents and two sisters, constantly being the "new girl in school". Acting wasn't a significant part of her life until her early twenties, when she was deeply impressed by a Jerzy Grotowski theater production, which prompted her to pursue a career in acting. She trained as a classical actress and enrolled at the Actors Studio and with Lee Strasberg in New York City. During this period, she made several student films and directed and acted in various plays.
Her first major film role came in 1978's National Lampoon's Animal House, which became a huge hit and launched a generation of young stars. However, shortly after the film's release, Allen was struck by a rare and dangerous eyesight condition called keratoconjunctivitis. Fortunately, the condition subsided, and she was able to continue her rising career.
Lead roles in cult classics like The Wanderers and the controversial thriller Cruising followed, as did smaller parts in Woody Allen's Manhattan. Her performance in Rob Cohen's A Small Circle of Friends and her role in National Lampoon's Animal House caught the attention of Steven Spielberg, who cast her as the feisty heroine and co-star of Harrison Ford in his big-budget blockbuster Raiders of the Lost Ark, which became a huge hit in 1981-82 and is widely regarded as one of the greatest action-adventure films ever made.
Following the success of Raiders of the Lost Ark, Allen chose to spend more than two years out of the limelight, focusing on smaller, more personal projects. She won a major award for her performances on Broadway, received critical acclaim for her portrayal of Abra in the hugely successful ABC production of East of Eden, and had parts in two smaller films: Alan Parker's Shoot the Moon and Split Image, co-starring James Woods and Peter Fonda.
She returned to the mainstream in 1984 with Until September and Starman, co-starring Jeff Bridges and directed by John Carpenter. However, once again, she decided to leave the limelight for a couple of years to focus on stage work and some independent films. Since then, she has worked almost constantly, giving notable performances in Paul Newman's screen adaptation of The Glass Menagerie, the Christmas hit Scrooged, and Steven Soderbergh's underrated King of the Hill.
Karen Allen has been married to soap star Kale Browne since 1988 and they have a son, Nicholas. Apart from acting, she is also an accomplished singer, songwriter, and musician, and has played in a band with Kathleen Turner and recorded a duet with Jeff Bridges for the Starman soundtrack album.
She is also a writer, having written plays, screenplays, and poetry. Allen owns her own Ashtanga yoga enterprise and spends time at her Berkshire Mountains farm or Upper West Side Manhattan townhouse. The classically trained actress has a screenplay called "The Second Coming," which is currently being made into a movie.