ADHD is one of the most common psychiatric conditions seen in pediatric practices, affecting 4-12% of children. Many children with ADHD currently receive inadequate assessment, inappropriate treatment, and/or insufficient follow-up care. As a result, practice variation is widespread for children with ADHD, and children with ADHD may have undiagnosed psychiatric comorbidities and inappropriate pharmacotherapy. This randomized controlled trial aims to achieve sustainable reductions in medical errors in the treatment of attention-deficit/hyperactivity disorder (ADHD), through the use of information delivered by a real-time point of care hand held computer decision support device (DS-ADHD). The extensive decision algorithms embedded in our system will allow providers to adapt ADHD treatment to the specific needs of their patient. We will randomize providers in 3 primary care practices to DS-ADHD or usual care. We hypothesize that DS-ADHD will result in reduced medical errors and increased patient satisfaction with ADHD care. Specifically, we hypothesize that use of the DS-ADHD will make providers less likely to miss comorbidities common among children with ADHD; will make patients more likely to have follow-up visits in accordance with established guidelines; will increase patient satisfaction with their ADHD care; and will increase provider satisfaction and confidence regarding ADHD treatment.