During the past decade, there has been an increase in the diagnosis and treatment of Attention-Deficit Hyperactivity Disorder (ADHD). This syndrome, typically diagnosed in childhood, is characterized by inattention, hyperactive motor behavior, and distractibility. Current prevalence rates obtained in various countries generally exceed the 3–5% reported by DSM-IV. Reasons for increased ADHD prevalence include changes in diagnostic standards, overlap between ADHD and other externalizing disorders, nonspecific behavioral criteria, and the rapid effects of stimulant medication on cognitive functioning. However, social, cultural, and economic factors may also contribute to increased diagnosis. ADHD has become a common topic in the lay media. Popular discussions of ADHD may serve as a metaphoric expression of social anxieties, particularly with respect to children. At the same time, ADHD has rapidly become incorporated into a medical model, with emphasis on pharmacological treatment. Reductions in mental health and educational services, as well as economic pressures of managed care, may also contribute to medicalization of behavioral problems. Collaboration between psychologists and primary care physicians can lead to more accurate diagnosis and appropriate treatment of ADHD and related disorders.