Studies suggest that children (< or =21 years) of BP parents are at increased risk for developing mood and other disorders (e.g., disruptive, anxiety). Therefore, additional investigations are clearly warranted. In the context of current research on diagnosis, assessment, longitudinal course and comorbidity of childhood mania, the following suggestions for the design of future studies should be considered: 1) Phenotypic specification of bipolar manifestations (e.g., BP-I, BP-II, BP-NOS) in child/adolescent offspring and in bipolar parents themselves. 2) Control groups that are pediatric-age relevant and thus include attention-deficit hyperactivity disorder. 3) Assessments that include items for prepubertal mania and for onsets and offsets of all occurrences of symptoms and of environmental factors (e.g., life events) in offspring and in parents so that trajectories of overlap and sequence between child and parental mania can be investigated. 4) These detailed onsets and offsets of symptoms are also necessary to investigate prodromal manifestations of mania in the offspring. 5) Unaffected offspring present a unique opportunity to study pre- and postmorbid cognitive and physiological endophenotypes and structural and functional brain abnormalities. Findings from offspring studies will be crucial to inform research on the development of early intervention and prevention strategies.