Adolescence is a vulnerable developmental phase marked by physical, psychological, and social changes that rapidly expose young people to a wide range of new stressors. When differentiating between bipolar disorder and teenage "acting out," a careful history is important. Adolescent bipolar disorder is a psychiatric illness characterized by fluctuating episodes of mood elevation and depression that is frequently neither recognized nor formally diagnosed. Adolescents with bipolar disorder often manifest a more nonepisodic, chronic course with continuous rapid-cycling patterns than do adults. Pharmacologic treatment of adolescent bipolar disorder is difficult and often requires combination therapy to address comorbidities like attention-deficit/hyperactivity disorder and anxiety disorder. Adjuncts to pharmacologic treatment of bipolar disorder can be beneficial. Psychosocial treatments include family education, enhanced parenting techniques, stress management, and the development of effective coping strategies.