The authors analyze male sexual initiation as a time of acquiring knowledge, based on 62 ethnographic interviews with young men (18-24 years) in the cities of Porto Alegre, Rio de Janeiro, and Salvador, Brazil, as a stage in the GRAVAD Research Project. Adopting an anthropological and comparative perspective, the reports show that men's first sexual experience is a process of physical and social learning by which they acquire technical knowledge on the use of their bodies and skill to relate to others, especially women. These are important milestones in the passage to adulthood. In addition to differences in belonging to various socioeconomic segments, the authors focus on gender relations, especially models of masculinity, demonstrating that a young man's first sexual intercourse is a socially and symbolically striking moment, not limited to a single event, but an experience that involves different levels of learning as part of the process of becoming a man.