Originally from Georgia, Scarwid went north to New York and studied at Pace University and the American Academy of Dramatic Arts before working on stage in Woodstock, NY, for the National Shakespeare Conservatory and in regional theaters throughout the country. By 1976, she was in Hollywood where she made her TV debut in an episode of "Gibbsville", also Savage. In 1977, Scarwid was acting in TV-movies such as "In the Glitter Palace" and "Possessed" (both NBC). She made her feature film debut in Louis Malle's "Pretty Baby" (1978), playing Frieda, one of the ladies of the brothel in which Brooke Shields is raised. After "Inside Moves", Scarwid's rising star was dampened a bit by "Mommie Dearest". She was not seen on the big screen for a year, but returned in 1983 as a schoolteacher turned junkie in Francis Ford Coppola's "Rumble Fish", as Cher's lesbian lover in Mike Nichols' "Silkwood", and as an alien disguised as Paul LeMat's wife in "Strange Invaders". She seemingly made another offbeat choice in 1986 when she appeared as a defrocked novice who ends up in Room Number 1 of the Bates Motel in "Psycho III", which, like "Mommie Dearest," ended up appearing as if it were played for laughs. By the 90s, Scarwid was playing numerous mother roles: she was emotionally fragile mother to Jacob Tierney in Terence Davies' "The Neon Bible", Anna Chlumsky's neglectful mom in "Goldiggers: The Secret of Bear Mountain" and the concerned mother of AIDS-infected Joseph Mazzelo in Peter Horton's "The Cure" (all 1995).
Scarwid has mixed her film work with roles in TV longforms, particularly remembered as Catherine Banahan in "Studs Lonigan" (NBC, 1985). She was also Toby, one of the PLAYBOY bunnies encountered by Gloria Steinem in "A Bunny's Tale" (ABC, 1985). In the 90s, Scarwid moved into playing historic figures. She was Rose Kennedy to Patrick Dempsey's John F. Kennedy in "JFK: Reckless Youth" (ABC, 1993) and shone as Bess Truman opposite Gary Sinise in "Truman" (HBO, 1995), which earned her an Emmy nomination.