In summary, although there has been much progress, alcohol and other drug use and abuse in adolescents remains a major medical and public health problem. Epidemiological studies of adolescents and young adults provide important information about the frequency, quantity, and types of drugs used among these populations. A number of theories on causation and initiation of use of alcohol and other drugs have been postulated, and each adds important new information to the field. Impressive gains have been made in the identification of risk profiles which lead to alcohol and other drug use. Although this work has been comprehensive in its approach, studying the influences of family and peer factors, psychological and biological variables, and environmental and demographic characteristics, many questions remain unanswered with regard to the distinguishing features of those at risk who progress to problem use. Additionally, although treatment programs have been developed specifically to meet the special needs of adolescents, treatment outcome studies and better assessment procedures to determine which adolescents need which specific types of treatment are still needed. Finally, effective physician education strategies are needed to ensure appropriate practice behaviors among health care providers, who should be an important link in the coordination of efforts as the health care community responds to the problem of alcohol and other drug abuse.