In this article we analyze the historical and sociopolitical context under which the First Universal Races Congress (1911) took place, and also address the main issues debated in the conference by anthropologists, sociologists and social activists from different countries. We highlight the contributions of the physicians and anthropologists João Baptista de Lacerda (1846-1915) and Edgard Roquette-Pinto (1884-1954), who traveled to London as official representatives of the Brazilian government, and discuss some of the papers presented by leading authorities in the field of anthropology and the race studies. The papers presented at the conference were published in a volume edited by the English sociologist Gustav Spiller.