W. E. B. Du Bois is credited with debunking the social Darwinism pervasive in turn-of-the-century social and political theory, exposing the environmental causes of black disadvantage and undercutting claims regarding “inborn” racial deficits. This, however, misses the constructive role that Darwinism played in his account of racial advancement. This article shows how Darwinism, eugenics, and race science shaped Du Bois’s conceptualizations of race and of racial uplift. Darwinism, I argue, informed his analysis of the harms that slavery and segregation visited on black Americans. It also influenced his defense of democratic equality: setting aside its other virtues, democracy would remove “artificial” constraints on the competitive struggle, enabling the best of white and black races to succeed. It was, then, eugenically advantageous. Against the common view that Du Bois rejected social Darwinism and eugenics, I demonstrate that their relationship was far more ambivalent and that his racial politics appealed to them.