This dissertation explores the relationship between social boundaries, social capital, and organizational stigma. Through an abductive study of the integration of Major League Baseball in 1947 and subsequent demise of the Negro Leagues, I show that as individuals and groups gain access to mainstream opportunities, organizations associated with the group may face stigma arising from within the stigmatized group. Chapter 1 motivates the dissertation. In Chapter 2, I summarize prior work on organizational stigma and destigmatization. In Chapter 3, I introduce my context of interest by tracing the history of racial exclusion in baseball from the sport’s invention in the 19th century to the end of World War II. In Chapter 4, I examine baseball coverage in black newspapers. I argue that newspapers elevated Jackie Robinson and other MLB trailblazers as visible exemplars whose success in integrated spaces provided a new template for conduct. Chapters 5 and 6 feature empirical extensions of these insights. In Chapter 7, I discuss the wide-ranging impact of the MLB trailblazer prototype and explore the generalizability of my arguments. Taken together, these findings suggest that early stages of identity group destigmatization may paradoxically undermine important economic and cultural pillars within the group.