In Brazil, the country with the largest population of African descent in the Americas, the idea of race underwent a dramatic shift in the first half of the twentieth century. Brazilian authorities, who had considered race a biological fact, began to view it as a cultural and environmental condition. Jerry Dávila explores the significance of this transition by looking at the history of the Rio de Janeiro school system between 1917 and 1945. He demonstrates how, in the period between the world wars, the dramatic proliferation of social policy initiatives in Brazil was subtly but powerfully shaped by beliefs that racially mixed and nonwhite Brazilians could be symbolically, if not physically, whitened through changes in culture, habits, and health. Providing a unique historical perspective on how racial attitudes move from elite discourse into people’s lives, Diploma of Whiteness shows how public schools promoted the idea that whites were inherently fit and those of African or mixed ancestry were necessarily in need of remedial attention. Analyzing primary material—including school system records, teacher journals, photographs, private letters, and unpublished documents—Dávila traces the emergence of racially coded hiring practices and student-tracking policies as well as the development of a social and scientific philosophy of eugenics. He contends that the implementation of the various policies intended to “improve” nonwhites institutionalized subtle barriers to their equitable integration into Brazilian society.