Early on, Hamilton set her sights on classical theater. In one of her first notable roles, she played opposite Kevin Kline in Measure for Measure in the New York Shakespeare Festival. Her performances in Much Ado About Nothing, Tartuffe, Reckless, Family of Mann, and Two Gentlemen of Verona, earned her a reputation as a serious dramatic actor. In 1995-96, her portrayal of a young, aspiring South African singer in Athol Fugard's Valley Song garnered an Obie Award, the Clarence Derwent Award, the Ovation nomination for best Actress, and a Drama Desk nomination. More recently, Hamilton earned critical acclaim, her second Obie, and a Lucille Lortel Award nomination for her role as Suzanne Alexander in Adrienne Kennedy’s, The Ohio State Murders.