This Multi-model Treatment Study of children with Attention Deficit Hyperactivity Disorder (ADHD) was sponsored by the National Institute of Mental Health (NIMH) to assess the effectiveness of various treatment protocols for those children diagnosed with ADHD. Children with ADHD may appear functionally impaired in many areas and may engage in a broad range of problem behaviors that frustrate and disrupt family, school, and peer relationships. The implications of this study will help improve educational outcomes and reduce delinquent behavior in children who have the disorder. The study consisted of nearly 600 children, ages 7- to 9-years old, randomly assigned to 1 of 4 treatment groups: (1) medication management only; (2) behavioral treatment only; (3) a combination of medication and behavioral treatment; and (4) routine community care (the control group). There were six study sites throughout the U.S. and Canada engaged in the study. Study results indicate that two forms of treatment, carefully administered medication alone or in conjunction with intensive behavioral treatment program, were significantly more effective in reducing the symptoms of ADHD. Also, children in the combined treatment group (medication plus behavioral treatment) received, on average, significantly lower doses of medication than those receiving medication. In other areas of functioning (oppositional-aggressive behaviors, social skills, parent-child relationships, and academic achievement), few differences among the study treatments were found except in three areas: combined treatment was superior to behavioral treatment for children’s anxiety symptoms, oppositional and aggressive symptoms, and reading achievement. Only combined treatment fared significantly better for all five areas of functioning. Future research will study subjects into adolescence, conducting repeated assessments on the four treatment strategies.