Many adolescent health problems are linked with educational performance, family relationships, poverty, and the general lifestyles that adolescents experience in their communities. Although serious, chronic medical and psychiatric disorders affect about 6 percent of the adolescent population, many more adolescents are at risk for death and for poor health outcomes that are not primarily biomedical in origin. The "social morbidities" (suicide, homicide, substance abuse, sexually transmitted diseases, unintended pregnancy, and HIV/AIDS) are primarily the result of social environment and/or behavior. Medical and social science research has revealed two disturbing trends: many health problems are affecting adolescents at younger ages; and many adolescents are simultaneously involved in several health-threatening behaviors. Chapter 1 of this volume examines the prevalence and severity of adolescent health problems and whether adolescents are getting the health services they need. Chapter 2 describes how violence, physical and sexual abuse, drug use (including alcohol and tobacco), and sexual activity threaten the well-being of adolescents. Chapter 3 reveals trends in adolescent health, how it has improved and how it has gotten worse. Chapter 4 identifies the degree to which adolescents are at risk for health threats depending on age, race, sex, and family income. Chapter 5 describes efforts by public and private groups and suggests items for organized medicine's agenda to improve adolescent health. (IAH)