Given the evidence that stimulant therapy with MPH improves driving performance and that once-daily OROS MPH improves driving performance and is more effective in the evenings compared with the IR formulation, we recently studied the effects of 2 long-acting stimulant formulations—once-daily OROS MPH and mixed amphetamine salts extended release (se AMPH ER, ADDERALL® XR)—on simulated driving performance in adolescents with ADHD to compare how each affected adolescent driving performance. This study indicated that medication improved driving performance and neuropsychological functioning relative to placebo, and that generally OROS MPH (Concerta) led to greater improvement. However, individual differences were such that a minority of subjects performed better when taking se AMPH ER (Adderall XR).