A quasi-experimental design is used in this study to evaluate the “Entre Nous Jeunes” peer-educator program to promote STI/HlV-preventive behaviors in Nkongsamba, Cameroon. The main objective of the study is to assess whether the young people exposed to a peer educator gained greater knowledge and practiced more protective behaviors than did those in the control community and those who were not exposed. During the 18-month intervention period, the peer educators were able to reach a large number of young people, specifically those who were sexually experienced and in need of reproductive health information. Multivariate analyses indicate that contact with a peer educator is statistically significantly associated with greater spontaneous knowledge of modern contraception, the symptoms of sexually transmitted infections, and greater use of modern contraceptives, including the condom. In the absence of a peer-education program, current contraceptive use in the intervention community would have been significantly lower.