The youngest of eight children, Harley Jane Kozak was born in Pennsylvania. Sadly, her father died just a year after she was born, prompting Kozak's mother to move the family to North Dakota, and later to Lincoln, NE, where Kozak would spend most of her childhood. Later deriving her stage name from the legendary Harley Davidson motorcycle series, Kozak made her on-stage debut at five-years-old, when she appeared in a college opera production of Dido and Aneas. Before finishing elementary school, she had landed a recurring role as a fifth grader on the educational TV show Music With Mrs. Kozak; she also joined the Nebraska Repertory Theater as a tap dancer by her junior year in high school.
After high school, Kozak moved to New York City, where she studied acting at the highly reputed NYU School of the Arts. After finishing her college studies, Kozak made her feature-film debut in The House on Sorority Row (1983), and landed a regular role on the long-running daytime soap Guiding Light before joining the cast of NBC's Santa Barbara. Her character met a sticky end, even for soap standards -- a neon letter "C" fell from a hotel marquee and crushed her to death. By the late '80s, Kozak had made a tiny appearance in a big film (1989's When Harry Met Sally with Billy Crystal and Meg Ryan); made a larger appearance in a supporting role on Parenthood (1989); and finally starred opposite Jeff Daniels in director Frank Marshall's horror comedy Arachnophobia (1990). Kozak showed her diversity in her following roles, which ranged from sports comedies (1991's Necessary Roughness) to action thrillers (The Taking of Beverly Hills, also 1991) to the sci-fi romance The Android Affair (1995). Kozak also portrayed a bored wife in The Favor (1994) with Brad Pitt, and despite the movie's lack off significant mainstream success, the actress was praised for her work in it. After starring in a variety of film and made-for-television feature roles, Kozak signed on for the ill-conceived ABC sitcom The Secret Lives of Men opposite Peter Gallagher in 1998. In 2004, she took a new turn professionally with the publication of her debut novel, Dating Dead Men. Kozak lives in California with her husband, two dogs, and a cat.