The aim of the study was to identify the factors associated with age of onset of sexual aggression, and variety and desistance of criminal activity, among adolescent sexual aggressors. The sample consisted of 351 adolescents (M age = 15.8 years, SD = 1.8) who were assessed in an outpatient psychiatric clinic between 1992 and 2002. Recidivism data were collected after a mean follow-up period of 8 years. Hierarchical logistic regression analyses demonstrated that some variables related to childhood and adolescent development discriminated among participants who went on to follow different criminal activity trajectories. Indices of early antisocial behaviors (aggressive behavior, antisocial traits) were associated with early activation of a pattern of sexual offending as well as a polymorphic criminal career in adolescence. Findings supported previous research indicating that most adolescent sexual offenders who persist in a criminal career commit a variety of offenses and do not specialize in sexual crimes. (Published Abstract)