Founders of the North American Society for Sport Management (NASSM) set out to realize a future in which the management of sport was part of a broader vision that included exercise, dance and play. However, the organization quickly became untethered from this broad interpretation of sport management. In this mixedmethod historical research and Delphi study, 10 founding members of NASSM explain the underlying reasons why NASSM leaders redirected the organization�s focus over time. Drawing from the literature on institutional legitimacy as a lens to understand the development of NASSM, the findings suggest an emphasis on commercial sport emerged over that of exercise, dance, and play. This emphasis was perceived to offer a more sustainable niche within the crowded sport and physical activity academic society continuum. Shaped by market- and culture-driven processes, NASSM�s legitimacy-seeking efforts ultimately catalyzed a narrowing of the organization�s scope.