Being born the oldest of four kids to a surgeon father, Marilyn graduated from high school in Grosse Pointe, then attended Miami University (Ohio) and eventually graduated from the University of Colorado with a Bachelor of Humanities degree. After a stint in New York City waiting on tables and working as an office clerk in-between acting jobs, she was signed with 30 other performers to Columbia Pictures' Talent and Development Workshop and sent to Los Angeles. The program folded when the executive, who ran the studio at the time, resigned.
Nevertheless, she still managed to land an agent and began acting In television episodes. Her performances in the Lou Grant: Harassment (1980) episode of the CBS-TV series Lou Grant (1977) and in the M*A*S*H episode "Good-Bye Radar: Part 1" (1979) as Lieutenant "Patty" Haven were especially strong. She landed roles in two short-lived prime-time soaps, Secrets of Midland Heights (1980) for CBS and King's Crossing (1982) for ABC. She worked steadily throughout the 1980s.