Objective: Stimulant medication is an efficacious and first-line approach to treating ADHD in adolescence. However, less is known about the effectiveness of this approach as a treatment in real-world settings. The complicated nature of the secondary school environment and documented adolescent nonadherence with stimulant medication may undermine the exportability of this approach. Method: This study investigates stimulant medication effectiveness and adherence in a sample of adolescents with ADHD who were observed in their natural secondary school environment. Results: Results indicated that the effect of stimulant medication on adolescent functioning is smaller in naturalistic settings than in previous analogue studies. Long-acting pemoline produced greater adherence than the short-acting methylphenidate (MPH), but parents and adolescents preferred the short-acting MPH. Conclusions: Overall, adolescents reported very low satisfaction with stimulant medication. Findings are discussed. (J. of Att. Dis. 2013; XX(X) X-XX)