In 1940 Carole starred in the sex-change comedy Turnabout. She was under contract with Hal Roach when she made the movie. Carole is Sally Willows, an unhappy housewife who magically switches bodies with her husband. John Hubbard plays Sally's husband Tim who must act like a woman when an angry genie makes the couple trade places. Carole and John also worked together in Road Show. Turnabout was based on the book by Thorne Smith. The cast includes Adolphe Menjou, Mary Astor, Marjorie Main, Donald Meek, and Margaret Roach (Hal Roach's daughter). Carole became close friends with Margaret. John and Carole had to learn each others lines because their voices were dubbed in many scenes.
Carole studied John's mannerisms so she would be believable playing a man trapped in a woman's body. Turnabout was produced and directed by Hal Roach. He gave Carole the nickname "The Ping Girl" but she begged the press not to call her that. Turnabout was filmed in February 1940. Before filming began Carole lost twenty pounds. The costumes were designed by Royer. Turnabout was released on May 17, 1940. Censors changed some controversial scenes before they would let the film be released. Turnabout was a hit and Carole got rave reviews for her performance. In 1979 Turnabout was made into a television series starring Sharon Gless and Rick Springfield.