Sex and HIV Education Programs for Youth: Their Impact and Important Characteristics is a review document developed by D. Kirby, B. A Laris and L. Rolleri from ETR Associates (Education, Training and Research Associates) with the support of USAID (United States Agency for International Development) through FHI (Family Health International)/YouthNet Project, in 2006. This current review report reviews the existing literature on the effects of these curriculum-and group-based sex and HIV education programs on sexual risk behavior among young people in both developed and developing countries. The review analyzed the impact these programs had on sexual risk-taking behaviors among young people. The methods used in this review included three primary activities: 1) comprehensively searching for and retrieving all studies meeting specified criteria, 2) coding all the results of those studies, and 3) conducting a content analysis 19 curricula that were clearly effective at changing behavior. The results are divided into four sections: 1) characteristics of the studies reviewed, 2) impact of programs on sexual risk behaviors, pregnancy and STI rates, 3) impact of programs on mediating factors for sexual risk behaviors, and 4)characteristics of the curricula-based programs that positively affected behaviors. The document presents then the analysis of these effective curricula which led to the identification of 17 common characteristics of the curricula, including their development, content and implementation. It shows that programs that incorporated these characteristics were identified as successful and were much more likely to change behavior positively than programs that did not incorporate many of these characteristics. The document is prepared mainly for curriculum planners and implementers regarding sex and HIV education and who want to reduce adolescent sexual risk behaviors.