This study was designed to establish and validate a multidimensional empirically based typology of clinically referred adolescent substance abusers. A total of 141 adolescent substance abusers, most of whom were male, African-American, and juvenile justice involved, comprised the study sample. Youth and their parents completed comprehensive assessments at intake to treatment, discharge, and at 6 months and 12 months post-discharge from treatment. Adolescents were classified based on individual and family risk factors, associated problems, and severity of substance use. Variables included in the 2-stage cluster analysis included adolescents' substance use, psychiatric disorders, and legal involvement; peer substance use; family substance abuse; parental psychopathology; and family conflict. Three groups emerged: Juvenile Justice Involved Substance Abusers, with the lowest level of overall risk but highest juvenile justice involvement; Comorbid Substance Abusers, with the greatest family risk and individual psychopathology; and Heavy Substance Abusers, marked by serious substance abuse and peer substance use. Discriminant and predictive validity of the typology were established. This multidimensional typology of teenage substance abusers suggests that risk factors, associated problems, and substance use severity are all critical in assessing and treating this heterogeneous population. Different intervention strategies may be appropriate for these subgroups of adolescent substance abusers. (Editor's abstract.)