To determine the psychiatric characteristics of this population, 58 outpatient male adolescent sex offenders were interviewed with structured instruments. Conduct Disorder was the most common diagnosis, while rates of other disorders were much lower than in earlier studies. The high incidence of Conduct Disorder suggests that many sex offenses committed by adolescents are part of a pattern of poor impulse control and social behaviors. This seems particularly true in the case of the rapists in this sample, three quarters of whom had full Conduct Disorder. The fact that nonrapists had a much lower incidence of Conduct Disorder suggests that, for many of these boys, there may be other factors that led them to engage in inappropriate sexual behavior. Future studies will need to compare subgroups of adolescent sex offenders with respect to long-term recidivism in response to specific treatment interventions. 3 tables, 14 references.