Evaluate whether stimulant medication improves acquisition of academic material in children with attention deficit hyperactivity disorder (ADHD) receiving small-group, content-area instruction in a classroom setting. Participants were 173 children between the ages of 7 and 12 years old (77% male, 86% Hispanic) who met Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for ADHD and were participating in a therapeutic summer camp. The design was a triple-masked, within-subject, AB/BA crossover trial. Children completed two consecutive phases of daily, 25-min instruction in both (a) subject-area content (science, social studies) and (b) vocabulary. Each phase was a standard instructional unit lasting for 3 weeks. Teachers and aides taught the material to small groups in a summer classroom setting. Each child was randomized to be medicated with daily osmotic-release oral system methylphenidate (OROS-MPH) during either the first or second of the instructional phases, receiving placebo during the other. Medication had large, salutary, statistically significant effects on children’s academic seatwork productivity and classroom behavior on every single day of the instructional period. However, there was no detectable effect of medication on learning the material taught during instruction: Children learned the same amount of subject-area and vocabulary content whether they were taking OROS-MPH or placebo during the instructional period. Acute effects of OROS-MPH on daily academic seatwork productivity and classroom behavior did not translate into improved learning of new academic material taught via small-group, evidence-based instruction.(PsycInfo Database Record (c) 2022 APA, all rights reserved)