How does our understanding of the reality (or lack thereof) of race as a category of being affect our understanding of racism as a social phenomenon, and vice versa? How should we envision the aims and methods of our struggles against racism? Traditionally, the Western political and philosophical tradition held that true social justice points toward a race-less future — that racial categories are themselves inherently racist, and a sincere advocacy for social justice requires a commitment to the elimination or abolition of race altogether. This book focuses on the underlying assumptions that inform this view of race and racism, arguing that it is ultimately bound up in a politics of purity — an understanding of human agency, and reality itself, as requiring all-or-nothing categories with clear and unambiguous boundaries. Racism, being organized around a conception of whiteness as the purest manifestation of the human, thus demands a constant policing of the boundaries among racial categories. Drawing upon a close engagement with historical treatments of the development of racial categories and identities, the book argues that races should be understood not as clear and distinct categories of being but rather as ambiguous and indeterminate (yet importantly real) processes of social negotiation. The author takes seriously the way in which racial categories, in all of their variety and ambiguity, situate and condition our identity, while emphasizing our capacity, as agents, to engage in the ongoing contestation and negotiation of the meaning and significance of those very categories.