This presentation reviews studies exploring reasons for the increased diagnosis of bipolar disorder in children and adolescents. It is hypothesized that the increase is due to a lack of understanding how bipolar disorder affects this age group. Strengths and limitations of studies are examined. Evidence indicates bipolar disorder beginning in childhood may be a more severe form of the illness than in older adolescents. The controversy around diagnosing children/adolescents separately from adults stems from debates around separately defining and criteria for the two age groups.