In order to contribute to the more general reflection on the links between science and politics, I discuss in this article how, in practice, social anthropologists build their knowledge. Moving continually through the fluid boundaries between LGBT activism and academic reflection, Brazilian social anthropologists became important actors in the process of promoting “homosexual citizenship” in Brazil. I focus in more detail on two different historical contexts: the late 1970s and mid-1980s, when the homosexual movement began to be organized in Brazil; and the first decade of the 2000s, when I began to developed my own research. © 2016, Universidade Estadual de Campinas UNICAMP. All rights reserved.201647