This prospective study involved 59 adolescents with drug and alcohol disorders who had just completed outpatient treatment. They participated in a comprehensive baseline assessment, and then participated in monthly telephone assessments of substance use and reasons for use. Despite their recent treatment, two-thirds (66%) of the participants in this study had relapsed to drug use within 6 months. The median time to drug relapse was only 54 days (+/-14 days), or slightly less than 2 months. The three most commonly given reasons for relapse were social pressure, withdrawal, and negative affect. These findings provide a first confirmation of the results of S.A. Brown [Recovery patterns in adolescent substance abuse. (1993). In J. S. Baer, G. A. Marlatt, & R. J. McMahon (Eds.), Addictive behaviors across the life span (pp. 160-183). London: SAGE.] in showing that most adolescents relapse quickly following treatment for substance use disorders.