The adolescent drug treatment outcome research literature primarily focuses on short-term follow-up periods (e.g., 1 year). This study extends the said literature by describing the pattern of drug use at 1, 4, and 5.5 years in three groups of adolescents: a Treatment group, which underwent a 12-step-based drug treatment program (n = 159); a Waiting List group (n = 62); and a Community Control group (n = 94). The Treatment group consistently showed significantly lower levels of drug involvement than the Waiting List group. However, at all points, both the Treatment and Waiting List groups showed higher levels of drug use than the Community Controls. Within the Treatment group, completing treatment and involvement in aftercare were positively associated with improved outcomes. The treatment implications of the study are discussed.