Who are the young people reached by peer education programs and/or by youth centers? The present study intends to better know about the activities of the peer educators who are involved in organizations that promote reproductive health information and services in three West African countries. A special research tool was created to collect data to evaluate the composition and characteristics of the populations that such programs reach; therefore, to evaluate the populations left behind. We found that the typical profile of individuals in contact with peer educators or attending youth centers tended to be males aged 15 and more, schooled or highly educated, never married, and living in urban areas. We also found a relationship between peer educators' and peers' socio-demographic characteristics in rural Burkina Faso and urban Guinea Bissau. Finally, the main topics discussed included HIV/AIDS and Sexually Transmitted Infections, but omitting other aspects of sexual and reproductive health.