Race is one of the most common variables in the social sciences, used to draw correlations between racial groups and numerous other important variables such as education, healthcare outcomes, aptitude tests, wealth, employment and so forth. But where concern with race once reflected the view that races were biologically real, many, if not most, contemporary social scientists have abandoned the idea that racial categories demarcate substantial, intrinsic biological differences between people. This, in turn, raises an important question about the significance of race in those social sciences: if there is no biological basis of race, why are racial categories useful to social scientists? More specifically, in virtue of what are racial categories a successful basis of informative, important social scientific generalizations? 2 We’ll call this social science’s race puzzle.