The focus is on complex medical and behavioral problems in adolescent health care that are faced by primary practitioners in pediatrics, family practice, internal medicine, college and school health, nursing, and psychology. The opening article defines and reviews the concept of risk-taking during adolescence and presents a theoretical model for understanding mechanisms associated with the onset and maintenance of risk behaviors. Individual risk behaviors include sexual behavior, substance use, and vehicle use. The next article reviews the demography and predominant mortalities and morbidities of adolescence including motor vehicle accidents, suicide, homicide and violent crime, pregnancy, sexually transmitted diseases, alcohol and drug use, tobacco use, and runaway and homeless youth. Subsequent articles look at the developmental basis of adolescent risk-taking, the role of social and cultural factors, adolescent involvement in violent family relations as victims and as perpetrators, teenage gang behavior, adolescent depression and suicide, adolescent pregnancy prevention, and substance abuse prevention in children and adolescents. Other articles discuss biological, sociological, and psychological perspectives on whether adolescents are growing up too fast; the role of private practitioners in developing solutions to adolescent problems; and the effect of television and radio on adolescent sex and drug behavior. References, tables, and figures