In 1986, Arnold appeared as Crystal, one of the three chorus girls who perform R&B numbers in Frank Oz's film musical "Little Shop of Horrors" (1986) along with future "Martin" co-star Tisha Campbell. Arnold was only sixteen at the time of filming, and her career continued steadily after that, with a role or two almost every year, including the films "How I Got into College" and the Paul Mazursky/Woody Allen collaboration "Scenes from a Mall" (1991). In February 1987 Arnold scored her first big break on television, with a permanent role on the soap opera "Ryan's Hope". Her critically lauded role, as young heroine Zena Brown, landed her a Daytime Emmy Award nomination in 1988. She continued in the role until the series ended in January 1989. Later that year, Arnold was cast as Sharla Valentine, a high-school friend of Emily Ann Sago (played by Liz Vassey) on the ABC-TV daytime drama "All My Children". She continued in the role until 1991.