AbstractThe institution of berdache in aboriginal North America is a relatively well‐known phenomena among social scientists, yet a thorough, comprehensive investigation of the institution is lacking. In general, it involved a socially recognized means by which an individual might assume the dress, role, and status of the opposite sex. In this paper, the institution of berdache among the Plains Indians is examined. In Part I, the concept of berdache is more clearly defined; in Part II, the Plains berdache is examined in more detail (including specific ethnographic examples of the institution from several Plains tribes, and a brief discussion of reservation berdaches); Part III consists of an analysis of the institution in terms of Culture and Personality theory. The author suggests that the role of berdache served both personal and social functions in Plains Indian society.