Amanda's first stage role was in Artichoke at the Manhattan Theatre Club in 1979, and followed this in the same year with A Month in the Country, which also starred her mother, Tammy Grimes. In 1980 she appeared in "The Rabbit's House", part of Alice in Concert and in The Member of the Wedding in Hartford. She made her Broadway debut starring as Jo, the role made famous by Rita Tushingham, in the revival of the play A Taste of Honey in 1981. She won the Theatre World Award, The Outer Critics Circle Award and Tony and Drama Desk nominations for this role. Then in 1982, Amanda won the Tony Award, Drama Desk, Outer Critics and Boston Critics Award for her performance as Agnes in Agnes of God. The following year she appeared opposite Jessica Tandy as Laura in the Broadway revival of the Glass Menagerie, but also starred as Juliet in Romeo and Juliet at the La Jolla Playhouse. Two years later, in 1985, she acted in Sam Shepard's A Lie of the Mind and in Beth Henley's Life Under Water. In 1986 she appeared in You Never Can Tell and one year later she received her third Tony nomination for her role opposite Peter O'Toole in Pygmalion, and she also starred in The Milk Train Doesn't Stop Here Anymore. In 1990 she appeared with Tess Harper in another Beth Henley play, Abundance. Later she toured as Emily Dickinson in .The Belle of Amherst. She appeared off Broadway in NYC with Sam Shepard, from October. 1998 thru January 17, 1999 in the hit play Killer Joe. In the year 2003, Amanda appeared as Sonya in the Chekhov play "Uncle Vanya" at the McCarter Theater in Princeton, New Jersey and at the La Jolla Playhouse in La Jolla, California. was scheduled to play in the off-Broadway hit "Bug" in 2004, but left the cast just before the opening due to 'creative differences'. Amanda has since appeared at the Stratford, Ontario stage in "The Lark", and at the Hartford Stage in a very successful role in "Summer and Smoke".