There is increased recognition that bipolar disorder has an early age of onset. The prevalence of bipolar disorder in prepubertal children has not been determined, however the prevalence in adolescence is ˜1%. Bipolar disorder in children poses a diagnostic challenge since the symptoms may differ from those in late adolescence and adulthood. Comorbid disorders, such as attention-deficit/hyperactivity disorder, further complicate both the diagnosis and course of the disorder. There is increasing evidence of the chronicity and severity of this disorder in youths. Bipolar disorder significantly disrupts a child's psychosocial development including impairments in academic functioning, family functioning, and relationship with peers. Although this disorder has significant morbidity in children and adolescents, there is a paucity of controlled studies to assess the efficacy and safety of mood stabilizers in the treatment of this disorder in youths. The treatment literature consists largely of case studies, retrospective chart reviews, and open-label studies. There is a compelling need for double-blind, placebo-controlled trials to determine whether commonly used medications to treat this disorder are significantly superior to placebo. Since many children in clinical practice require more than one psychotropic medication to adequately manage this disorder, studies of combination treatments are warranted. This review will provide an overview of the literature of bipolar disorder in children and adolescents, including discussion of the prevalence, diagnosis, epidemiology, course of the illness, and treatment issues.