Children with attention-deficit/hyperactivity disorder (ADHD) experience profound, sustained, and severe impairments in academic functioning and long-term progress, making the identification and evaluation of effective approaches critical. Therefore, it is surprising that such little empirical work has explored effective intervention approaches related to learning. This proposal will investigate the efficacy of common academic accommodations (extra time, frequent breaks, low-distraction environment, and adaptive furniture) provided for children with attention- deficit/hyperactivity disorder (ADHD) as well as classroom behavior management positive supports and medication. There has not yet been a rigorous trial that investigates these interventions alone and in combination with one another for children with ADHD in standard educational settings. Thus, in this proposed study, the efficacy of commonly employed academic accommodations, behavioral support interventions, and medication will be rigorously evaluated in a within-subject design in a classroom setting conducted under well- controlled conditions in a summer treatment program setting. Specific aims for the project include an evaluation of the single and combined effects of behavioral supports, medication, and academic accommodations. Further, the moderating effect of child characteristics using standard diagnostic procedures as well as baseline neurocognitive functioning will be explored. Participants will be 288 children (grades K-5; 72 per year for four years; 36 per site), diagnosed with ADHD. At baseline, information on comorbidities (specific learning disability, disruptive behavior disorder) and neurocognitive impairments (processing speed, working memory, reaction time variability, inhibitory control and attention) will be measured and evaluated as moderators. Then, in a within-subject design, all children will receive each level of the behavior modification accommodations (i.e., no positive behavioral supports, positive behavioral supports), each level of medication (i.e., placebo, .3 mg/kg methylphenidate) and each level of the academic accommodations (i.e., extended time, adaptive furniture, frequent breaks, preferential/low distraction seating vs. a standard classroom environment). Measures of key outcome will include objective measures of behavioral and academic functioning. These include observations of behavior in the classroom (i.e., on-task behavior) and academic productivity (i.e., work completion) in independent seatwork and group instruction settings.