Children with ADHD have been widely reported to overestimate their abilities in social and academic domains, but a similar overestimation of physical abilities has not been examined. Twenty-four elementary school-age boys with ADHD and fifteen boys without ADHD were compared on their ability to accurately estimate their ability to complete four lab-based physical tasks, varying on three levels of difficulty: (a) within their ability, (b) 8% beyond their ability, and (c) 13% beyond their ability. Children with ADHD were significantly more likely than controls to overestimate their physical ability at difficult levels of the task. Implications of these results for preventing risky behaviors in children with ADHD are discussed.