The present study assessed possible predictors of relapse while in treatment and treatment completion among marijuana-dependent adolescents (N = 59) in an intensive outpatient substance abuse treatment program. Comorbid depression was associated with an increased likelihood of relapse and a higher total number of relapses. As expected, relapse while in treatment was associated with a reduced likelihood of successfully completing the treatment program. Comorbid attention deficit hyperactivity disorder (ADHD) was also associated with a lower likelihood of successful program completion. These findings add to a slowly growing literature regarding adolescent substance abuse treatment, and may help clinicians identify marijuana-dependent adolescents at greater risk of relapse or noncompliance.