This paper explores the disciplinary status of social psychology through an analysis of the history of the boundary relations of psychology, sociology, and social psychology. After outlining some research on the nature of scientific disciplines, on the role of rhetoric in the constitution of disciplines, and on “boundary work,” I consider the singular importance of social psychology as a discipline for the analysis of boundary relations, examining its units of analysis and its “disciplining.” The boundaries of the disciplines of social psychology were seen as fluid, contingent, local, and contestable, reflecting the thematic preoccupations, disciplinary origins, and meta-theoretical commitments of social psychologists, of the parent disciplines, and of those who represent disciplinary practices. © 2000 John Wiley & Sons, Inc.