Currently stimulants and atomoxetine are the most established treatments for attention deficit hyperactivity disorder (ADHD); more than 170 controlled studies with more than 9000 subjects have documented their efficacy in 50% to 70% of subjects. Although the stimulant medications tend to show a dose-related improvement in ADHD symptoms, atomoxetine is generally dosed based on weight. The literature clearly documents that stimulants improve not only abnormal behaviors of ADHD but also self-esteem, cognition, and social and family functioning. However, efficacy varies with age and psychiatric comorbidities. Although most of the existing studies are brief, an increasing number of long-term studies have documented persistent response up to 1 and 2 years. Recent studies are extending the knowledge of treatment to younger and older subjects, women, and ethnic minorities. Cognitive and cognitive/behaviorally based psychotherapies combined with medication may play a role in treating behavioral and organizational issues and comorbid psychopathology.