On the stage, she created the role of Ariadne in the 1983 Broadway musical Merlin. She was the first Éponine in the second United States tour of Les Misérables in 1988. Nicastro recorded four albums released on the Varese Sarabande label. Two albums, Toonful and Toonful Too, feature songs from animated musicals, Reel Imagination features songs from family musicals, and On My Own features songs from contemporary Broadway musicals, including her version of On My Own. They feature Paul Goldberg on drums and percussion, Walt Fowler on trumpet, Jimmy Hoff on bass, and Lanny Meyers piano/arranger.
She appeared, briefly, as the college sweetheart of Billy Crystal in When Harry Met Sally. In 1996 she played Snow White in Coach episode "Grimmworld" as the girlfriend of Michael "Dauber" Daubinski (Bill Fagerbakke). Nicastro also had a minor role in Full House as Roxanna. She also played Lois "Old Lady" Scranton on an episode of Who's the Boss?. From September 1989 to May 1990 she appeared as singer Sasha Schmidt on Santa Barbara during one of its Daytime-Emmy-award-winning years.
Nicastro died of breast and brain cancer on November 4, 2010, at home with her family. She was 50 years old. "For the Good of Our Country", an episode of The Event that originally aired November 15, 2010, is dedicated to her memory. The pilot episode of Fairly Legal, originally aired January 20, 2011, was dedicated to her memory and a character in the series Judge David Nicastro (played by Gerald McRaney) is named after her. Both series were executive produced by her husband Steve Stark.
