In the 1930s, Mary studied acting, and worked in summer stock theatre. In 1936, on the strength of her modeling, Mary was offered her first significant role in a film, Soak The Rich by Paramount Pictures. Soon after, she became a contract actress for Metro Goldwyn Mayer, and moved to California. In 1939 Mary appeared in the film Lady of The Tropics, produced by Sam Zimbalist, who was to become her husband. In 1941 MGM lent Mary to Warner Brothers for two films: Blossoms in the Dust and Shining Victory.