Abstract: This article takes a standpoint based in the human and social sciences to examine a decisive time in any research related to HIV-AIDS, ie, when healthy, seronegative individuals agree to take part in preventive clinical trials. The context of recruitment for such trials has been changing over the past several decades: the normalization of the epidemic after a period of sensationalism, the change in focus of social communities to other causes, the changes in the disease from a therapeutic point of view (new drug treatments and preventive drugs), the absence of compensation for participation in trials, the absence of any direct health benefits for the participants, and the fear of volunteers or the people in their lives of the idea of transforming their healthy body into a postexperimental body. Research on the prevention of HIV seems to be dependent on the consent of a limited number of people and groups because their reasons for taking part in such experiments, which are just as much personal as they are for the sake of science, are necessarily very particular. How can healthy individuals be recruited for preventive HIV trials? What is the social basis and what kind of mediation is involved in a mutual understanding between trial participants and investigators? Such questions are answered by the authors in this book, who approach the issues from a multidisciplinary and diachronic perspective.