The data indicated seven treatment-oriented youth prototypes that reflected the vast clinical differences among adolescents in treatment for SUD. Results indicated that the seven typologies were stable, valid, and they were able to discriminate court-mandated from non-court-mandated youth. The findings have implications for adolescent SUD treatment programs in that they identify the wide variation found in adolescent SUD problems. SUD programs serving youth are encouraged to develop different program tracks for different typologies or restrict services to the typology they are best at serving. Participants were 126 male and 79 female adolescents aged 12 to 18 years who were referred for substance abuse treatment and were recruited through their treatment program. Researchers administered the Comprehensive Adolescent Severity Inventory (CASI) to the 205 participants at a baseline assessment and then again 4 days later to assess test-retest reliability. Follow-up interviews were conducted at 1 and 6 months following program discharge for both treatment completers and noncompleters. In addition to completing the CASI at follow-up, biological measures (urine specimens and breathalyzer readings) were taken at the two follow-up points. Cluster analytic procedures were used to sort the 205 adolescent profiles from the 4 CASI dimensions (Delinquency, Psychosocial Functioning, Chemical Dependency, and Sexual Risk Behavior) into mutually exclusive groups. Data were also analyzed using multiple logistic regression models. Future research should investigate the effectiveness of treatment-matching whereby youth are matched to treatment programs based on their typology. Tables, references