Presented is a detailed case study of an 8-year-old socially withdrawn girl with elective mutism. Reviewed are early developmental data, and described are the therapeutic processes involved in her treatment in a psychiatric facility, including speech therapy and individual play sessions. Theoretical considerations on the origin of her mutism are discussed. The theory is set forth that she elected not to talk as a protective device against oral aggression in addition to a means of rebellion and a controlling device against her parents. (CL)