There is increasing popular interest in the phenomenon of the successful professional or businessman who switches careers in middle age. There is little hard data available about the phenomenon although there is a great amount of psychological conjecture. This paper briefly reviews the various theories that attempt to explain midlife career change, and then focuses specifically on white collar or professional workers, from ages 35 to 60. It deals with the following aspects: a workable definition of career as it relates to job and leisure; a conceptual framework of the process by which one seems to become a career changer (the framework views career changing as deviant); a review of current literature; theories about career change; constraints on career change; some proposals for intervention; and some of the developing social movement responses. (Author/NG)