Bipolar disorders are common, chronic illnesses that can develop in children and adolescents at early ages. However, diagnosing bipolar disorders in youths can be difficult because currently defined gradations of the disorder, including bipolar I and bipolar II disorders and bipolar disorder not otherwise specified, were not created with the developmental differences of children in mind. Children with major depression or attention-deficit/hyperactivity disorder plus a family history of bipolar disorder may be presenting with prodromal signs and symptoms of a bipolar disorder, although longitudinal studies are needed to clarify risk factors for developing bipolar disorders. Neuropsychological and biological markers may eventually aid clinicians in distinguishing bipolar spectrum disorders and offering early intervention for at-risk children and adolescents.