Bipolar disorder is a common condition with no recognized differences in prevalence between gender or ethnic groups. Probands are recruited without regard to sex, religion, race or ethnicity. This approach has, in the past, produced samples that are mostly European-American. Children are excluded because the diagnostic instruments used in this study are not validated in children. Moreover, participation in a family genetic study on bipolar disorder may pose additional risk for children, since they may be unable to understand what it means to be related to people with mental illnesses. Subjects who suffer cognitive impairment and are unable to provide an accurate psychiatric history are excluded since much of the diagnostic information relies on self-report and recall of past events. People too cognitively impaired to give their own consent are excluded.