Treatment and comparison groups were interviewed using a structured interview schedule designed to assess program outcomes, and participants were interviewed again 2 months after administration of the pretest. An aftercare post-test was administered to young people who were able to participate in the aftercare portion of the study. At the end of the aftercare interview, participants were asked to provide a urine sample. Young people who participated in the residential portion of the drug treatment program reported significantly decreased drug use and delinquency and increased cognitive decision-making skills. In addition, they demonstrated a longer period of time from entry into the study until rearrest than control young people. Results for the aftercare segment showed positive gains made while in the residential program were not bolstered through aftercare. Aftercare young people reported more delinquent behavior and demonstrated more involvement in drug-related crime than control subjects. Aftercare young people, however, exhibited less participation in crimes of an interpersonal nature. Supplemental data on interview scales and study findings are appended. 43 references, 7 notes, and 6 tables