The bipolar disorders are characterized by dramatic swings in mood that usually occur in cycles. A few adults and most children with this disorder experience rapid cycling of moods, with one cycle occurring each day or even three to four cycles in a day. The Diagnostic and Statistical Manual of Mental Disorders distinguishes four types of bipolar disorders. Three of the disorders differ from one another in the severity or the duration of their mood disturbance, and the fourth, "bipolar disorder not otherwise specified" (BPDNOS), is the diagnosis for people with significant bipolar symptoms that do not meet the criteria of the first three disorders. The most notable characteristic of children with a bipolar disorder is chronic irritability, which is often shown by anger and aggression. They are very active during their manic periods, and there is a driven quality to much of their activity. During these manic periods, children may often engage in dangerous feats without regard for risk. Most children who have bipolar disorder also have one or more other disorders, and many of these disorders share core symptoms with bipolar disorder. This article profiles the disorders often comorbid with bipolar disorder and discusses differential diagnosis. Other topics addressed are obstacles to recognizing bipolar disorder or mania in children and adolescents, behaviors associated with bipolar disorder and mania in children, and therapeutic interventions with children and their families. The latter interventions are discussed as pharmacotherapy and psychological interventions. A case study is included. 2 notes and 30 references