This dissertation is a re-examination of a group of doctors in Brazil in the second half of the nineteenth century called the Escola Tropicalista Bahiana. It uses new historiographical methods integrating medical history with social history, and raises fundamental questions about the meaning of the Tropicalista School within the political and social context of the Brazilian Empire. The methodology is informed by two key ideas: a rejection of simplistic explanations viewing medical science purely in terms of the rational advance of knowledge; and recognition of the close relationship between biological facts and the social construction of medical ideas.