While attention-deficit hyperactivity disorder (ADHD) has been traditionally viewed as a childhood ailment, longitudinal data suggest that it persists into adulthood for most affected individuals. Adult ADHD is now recognized as a legitimate diagnosis with clinical and epidemiological implications. It is estimated that 4% of American adults are afflicted by this disorder. There have been advances in adultADHD screening tools, diagnostic guidelines, medication delivery systems and psychosocial treatments. Despite these gains, there is great variability among clinicians in the diagnosis and treatment of adult ADHD. This article reviews controversies surrounding the diagnosis and treatment of adult ADHD and suggests strategies to overcome existing obstacles.