Proposed is a 5-year longitudinal, high-risk study examining the psychopathological and functional status of 800 children and adolescents (age 7-18.0 years old) of 400 parents with bipolar disorder(BPD) and compare them with 300 children of 150 non-bipolar, community control parents, with frequency matched on age, ethnicity, and neighborhood. The parents with BPD will be ascertained through the Stanley Center Community control parents will be ascertained using Cole's reverse directory. Offspring will be assessed at intake and annually, alternating between face-to-face and phone interviews, with standardized instruments to examine the differential incidence of psychopathology, dimensional measures of behavior and emotional psychiatric history. Offspring (an estimated 160 of 800) of BPD parents who at intake already have BPD (I, II, NOS and cycolthymia) will be followed through another grant Within the high-risk cohort, the investigators will examine the relationships between initial presentation and ultimate development of BPD and other mood disorders across different age groups. They hypothesize that offspring of BPD vs. offspring of control will show 1) Higher rates of incident BPD and other mood disorders and 2) Higher degree of behavior problems and mood dysregulation: 3) Within the offspring of BPD, incidence of BPD will be predicted by: early onset of parent's BPD, loaded pedigree for increased mood liability, increased exposure to familial and environmental negative events, and onset of puberty; and 4) Prepubertal onset vs. post-puberty onset BPD will show greater chronicity, frequency of mixed and rapid cycling presentations, and comorbid disruptive disorders. This unique prospective study will have important implications, and comorbid disruptive disorders. This unique prospective study will have important implications for early-detection, intervention, and prevention of childhood-onset of BPD.