The over-arching goal of this proposal is to examine a movement-based mindfulness training as a therapeutic intervention for children with ADHD. This approach is motivated by two complimentary lines of evidence: 1) Children with ADHD show impairments in motor control that parallel (and correlate with) core deficits in behavioral control that define the disorder. 2) Gains in cognitive and behavioral control have been observed in adults learning Tai Chi, dance, or meditation. These lines of evidence provide substantial motivation for our proposed investigation of movement-based mindfulness training in children with ADHD. Specifically, we propose to evaluate an established Tai Chi-based intervention. We chose this approach for a number of reasons: 1) Tai Chi is among the most well-established movement-based interventions with documented therapeutic effects, including cognitive effects. 2) While many movement-based approaches show evidence of yielding cognitive improvements Tai Chi provides excellent opportunities for engagement of 8-12 year old children in the form of the collaborative game "push hands." 3) Tai Chi instruction consists of gentle movements that can be practiced even by those with physical limitations, and is readily available in the United States so the protocols developed in this study will be straightforward to deploy at a national level.