This competing continuation of the study "Course and Outcome of Bipolar Youth" (COBY) will extend the follow-up of the sample for 5 more years. COBY is collaboration by the University of Pittsburgh, Brown University, and UCLA to investigate the longitudinal course of pediatric bipolar disorder (BP). As of 10/1/2005, we achieved our recruitment goal of 430 youth (186 children and 244 adolescents) with BP spectrum disorders (I, II and Not Otherwise Specified--NOS) using state-of-the-art clinical and analytic methodologies. Preliminary analyses of COBY's data are showing that pediatric BP is a rapid fluctuating and chronic illness associated with high psychosocial morbidity. However, limited data exists on the phenomenology, treatment responsiveness, and how course is influenced by the developmental transitions from childhood to adolescence, and adulthood. The unprecedented scientific and public health implications of COBY will accrue from ongoing observational data on a large, clinically diverse cohort of rigorously diagnosed subjects, which will enable us to: (1) describe the naturalistic course of recovery and recurrence patterns, as well as rapid mood changes, subsyndromal symptoms, and well periods into early adulthood;(2) identify predictors of long-term course and outcome;(3) describe psychosocial outcomes from childhood to early young adulthood;(4) describe treatments received and their effects in mediating course patterns;and 5) to explore domains of cognitive functioning across development in children and adolescents with BP spectrum disorders. Beyond the acquisition of new knowledge about long-term temporal patterns of pediatric-onset BP, an intrinsic value of extending the study of our cohort for another 5 years is that we will determine whether, and how, clinical phenotypes, psychopathological course trajectories, cognitive development and other important outcome variables change as probands move across developmental stages from childhood to young adulthood. Continued follow-up of the COBY sample at 6-month intervals using adaptations of instruments from the successful adult Collaborative Depression Study (CDS), will make it possible to develop more comprehensive knowledge on the above-noted aims given its large size, ascertainment from multiple sites, demographic and clinical diversity, and inclusion of subjects across the broad range of disease severity.