Before the age of five, Tracy had a film credit to her name. The daughter of singer Ricky Nelson and Kristin Harmon, she appeared as one of Henry Fonda's daughters in the movie Yours, Mine and Ours (1968). In 1982, she became the popular Valley Girl "Jennifer DeNuccio" on the television series Square Pegs (1982) which ran from 1982-83. This show made Tracy's name well-known in Hollywood. She made a few small appearances in movies while continuing to pursue television roles, and returned in series Glitter (1984). Two years later, she was in the Nick Nolte/Bette Midler movie Down and Out in Beverly Hills (1986). In 1987, Tracy was very sick and one month after her marriage to William R. Moses, she was diagnosed with Hodgkin's disease, but later cured. In 1989, she returned to television as "Sister Stephanie 'Steve' Oskowski" in Father Dowling Mysteries (1989). Since that time, she has appeared in a handful of television movies, including the TV series A League of Their Own (1993) and had a recurring role on Melrose Place (1992).