This monograph discusses how to protect adolescents by addressing health behaviors. Data come from the Add Health Survey, a comprehensive school-based study of adolescents' health-related behaviors. Secondary students answered surveys about their lives, health, friendships, self-esteem, and expectations for the future. School administrators completed surveys about school policies and procedures, teacher characteristics, health service provisions, and student characteristics. Students and parents completed interviews. Section 1 discusses resulting data on interrelationships among race, income, and family structure. Section 2 examines individual factors and friends and family influence on teen behavior. Both sections highlight cigarette use, alcohol use, suicidal thoughts and attempts, weapon-related violence, and sexual intercourse. While demographic factors influence behavior, they do not cause teens to engage in high risk behavior. It is necessary to move away from a focus on demographic factors in trying to understand adolescent health risk behaviors. Other factors are powerfully associated with exacerbating or minimizing risks to youth, and many are amenable to change. For example, being at academic risk was nearly universally associated with every health risk behavior studied. Friends and parents powerfully influenced teens' lives. When parents and families were involved, young people benefited. (SM)