This is a naturalistic treatment and follow-up study of youth with bipolar spectrum disorders (BSDs) across four US sites of The Childhood Bipolar Network (CBN). CBN sites have expertise in diagnosing, assessing, and treating BSDs in youth. The primary aims of this study are to (1) identify and reliably diagnose youth (ages 9 to 19 yrs) with full bipolar disorder (BD) and BSDs, and (2) examine predictors (e.g., mood instability, inflammatory marker C-reactive protein) of clinical outcome over a 12 month period. Participating youth will initially complete a screening that includes a structured diagnostic interview and a baseline blood draw to measure inflammatory processes. Youth with BSD and parents (80 families) will be asked to participate in multiple follow up research visits with interviews, rating instruments, and questionnaires. Per established CBN guidelines, study psychiatrists will provide and track medication management and sites will also track psychosocial treatments. This study ultimately aims to further understanding of best practice pediatric BSD psychiatric and psychosocial treatments and development of a standardized and validated set of clinical tools for patient assessment, diagnosis, and tracking.