Additional treatments with long-term benefit for attention-deficit/hyperactivity disorder (ADHD) are needed; one of the more promising is neurofeedback (EEG biofeedback), which has several randomized controlled trials showing significant benefit, but which are inconclusive because they were not double-blinded; the benefit could have been nonspecific (placebo response). Because of neurofeedback's labor-intensive cost (1 treatment costing as much as a month's medication), It is important to know how much specific benefit it yields. This 2- site placebo-controlled double-blind randomized clinical trial is the first to test for a specific benefit of neurofeedback with adequate power, the first designed and implemented collaboratively by experts in neurofeedback, ADHD, and clinical trials, the first to rigorously monitor quality not only of treatment, but also of placebo and blinding, and the first to follow up for 2 years to examine enduring effect; the results, whether positive or negative, will provide evidence for clinical practice and public policy regarding ADHD.