Du Bois’s The Souls of Black Folk (1903) is required reading in high school and college classes, and those who read past the first chapter know that the book is based in part on his sociological research in Georgia and elsewhere. Moreover, it has recently been demonstrated by Earl Wright II and Aldon Morris that Du Bois, through his pioneering Atlanta Conferences “for the study of the Negro Problems” (1898–1914), founded the first American school of sociology. But scholars have paid little attention to how Du Bois employed evolutionary ideas in his early sociological writings from 1897 to 1903. In this paper, I will demonstrate that Du Bois was interested in evolution in college, and was introduced to evolutionary debates in his Harvard classes; that both he and Alexander Crummell, one of his early mentors, sometimes echoed Herbert Spencer’s evolutionary language; that Du Bois viewed African-American institutions and African-American leadership as social evolutionary responses to a hostile environment; and that his sociological analysis of crime and poverty in The Philadelphia Negro (1899) depended on the idea of a mismatch between a social group and its environment. Thus, despite his later criticisms of Spencer’s “biological analogy” and “Social Darwinism,” Du Bois’s early sociology was developed in dialogue with the philosophy of evolution.