Children and adolescents who are the biological offspring of individuals with bipolar disorder (BD) (bipolar offspring) represent a population rich in potential for revealing important aspects in the development of BD. Multiple cross-sectional assessments of psychopathology in bipolar offspring have confirmed high incidences of BD, as well as mood and behavioral disorders, and other psychopathology in this population. Longitudinal studies of offspring have begun to shed light on precursors of BD development. Other assessments of bipolar offspring have included dimensional reports of psychiatric and psychosocial functioning, temperament assessments, and descriptions of family environments and parenting styles. Neurobiological studies in bipolar offspring are just beginning to yield findings that may be related to the underlying neuropathophysiology of BD. The future holds promise for longitudinal studies of bipolar offspring incorporating all of these facets, including genetic analyses, to further elucidate the factors involved in the evolution of BD. © 2003 Wiley-Liss, Inc.