This practice parameter reviews the literature on the assessment and treatment of children and adolescents with bipolar disorder. The parameter focuses primarily on bipolar 1 disorder because that is the type most often studied in juveniles. The presentation of bipolar disorder in youth, especially children, is often considered atypical compared with that of the classic adult disorder, which is characterized by distinct phases of mania and depression. Children who receive a diagnosis of bipolar disorder in community settings typically present with rapid fluctuations in mood and behavior, often associated with comorbid attention-deficit/hyperactivity disorder and disruptive behavior disorders. Thus, at this time it is not clear whether the atypical forms of juvenile mania and the classic adult form of the disorder represent the same illness. The question of diagnostic continuity has important treatment and prognostic implications. Although more controlled trials are needed, mood stabilizers and atypical antipsychotic agents are generally considered the first line of treatment. Although patients may respond to monotherapy, combination pharmacotherapy is necessary for some youth. Behavioral and psychosocial therapies are also generally indicated for juvenile mania to address disruptive behavior problems and the impact of the illness on family and community functioning.