The majority of regular adult smokers begin smoking in adolescence and there is a clear need for youth-targeted smoking cessation interventions. The present randomized, controlled trial tested the effectiveness of motivational enhancement therapy (MET) to reduce smoking among 81 adjudicated adolescents. Participants received either MET or an education control. Smoking abstinence, quantity, and frequency were assessed at 1 and 6 months post treatment. Results suggest that although between-group differences on outcome measures were not significant at follow-up, smoking behavior decreased in both groups with approximately 10% achieving 1-month smoking abstinence at 6-month follow-up. Furthermore, participant response to MET varied by level of alcohol use and impulsivity such that participants with lower levels of alcohol use and impulsivity had significantly greater response to MET. In contrast, participants who endorsed higher rates of alcohol use and impulsivity responded better to the control than the MET condition. Results suggest that MET may be an effective intervention for some adolescent smokers but may be contraindicated for adolescents who have concomitant problems with alcohol use or impulsivity.