The aim of this book is to provide developers of prevention or health promotion programs for school-age children with a summary of the international scientific and technical literature on interventions to prevent risky behaviors and how to implement them. The behaviors in question include violence directed against oneself or others, harmful use of psychoactive substances or early experimentation with them, dangerous behaviors on the road or during leisure activities, and risky sexual behaviors. The guide describes the stages and aspects of child and adolescent development, behaviors considered risky, and the determinants of health and these behaviors. It proposes prevention strategies considered effective and guidelines for developing, implementing, and evaluating interventions.