In treated cohorts, individuals with bipolar disorder are more likely to report childhood adversities and recent stressors than individuals without bipolar disorder; similarly, in registry-based studies, childhood adversities are more common among individuals who later become hospitalized for bipolar disorder. Because these types of studies rely on treatment-seeking samples or hospital diagnoses, they leave unresolved the question of whether or not social experiences are involved in the etiology of bipolar disorder. We investigated the role of childhood adversities and adulthood stressors in liability for bipolar disorder using data from the National Epidemiologic Survey on Alcohol and Related Conditions (n=33 375). We analyzed risk for initial-onset and recurrent DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) manic episodes during the study's 3-year follow-up period. Childhood physical abuse and sexual maltreatment were associated with significantly higher risks of both first-onset mania (odds ratio (OR) for abuse: 2.23; 95% confidence interval (CI)=1.71, 2.91; OR for maltreatment: 2.10; CI=1.55, 2.83) and recurrent mania (OR for abuse: 1.55; CI=1.00, 2.40; OR for maltreatment: 1.60; CI=1.00, 2.55). In addition, past-year stressors in the domains of interpersonal instability and financial hardship were associated with a significantly higher risk of incident and recurrent mania. Exposure to childhood adversity potentiated the effects of recent stressors on adult mania. Our findings demonstrate a role of social experiences in the initial onset of bipolar disorder, as well as in its prospective course, and are consistent with etiologic models of bipolar disorder that implicate deficits in developmentally established stress-response pathways.Molecular Psychiatry advance online publication, 22 April 2014; doi:10.1038/mp.2014.36.