The prevalence of attention deficit hyperactivity disorder (ADHD) symptoms and impairment in non-US children and adolescents was found to be similar to that in US children. Studies using DSM diagnostic criteria reported a range of prevalence rates for ADHD/ADD-H, with some countries showing lower prevalence figures than others. The results suggest that ADHD is not purely an American disorder and that the prevalence of this behavioral disorder in many countries is in the same range as that in the USA.