Attention-deficit/hyperactivity disorder (ADHD) affects 30 to 50 percent of adults who had ADHD in childhood. Accurate diagnosis of ADHD in adults is challenging and requires attention to early development and symptoms of inattention, distractibility, impulsivity and emotional lability. Diagnosis is further complicated by the overlap between the symptoms of adult ADHD and the symptoms of other common psychiatric conditions such as depression and substance abuse. While stimulants are a common treatment for adult patients with ADHD, antidepressants may also be effective. Cognitive-behavioral skills training and psychotherapy are useful adjuncts to pharmacotherapy.