For many years there has been debate over Attention-Deficit/Hyperactivity Disorder (ADHD) and whether this condition, which commonly afflicts adolescent children, is a medical or social condition and whether it is exclusively an American phenomenon. This article reviews the basis of ADHD's definition, diagnosis, treatment, and educational implications across three countries: the United States, Australia, and the United Kingdom. The differences in approach have clear and significant consequences for children and their futures.