Background: We report on mental disorders and violence for a birth cohort of young adults, regardless of their contact with the health or justice systems. Methods:We studied 961 young adults who constituted 94% of a total-city birth cohort in New Zealand, April 1, 1972, through March 31, 1973.Past-year prevalence of mental disorders was measured using standardized DSM-III-R interviews.Past-year violence was measured using self-reports of criminal offending and a search of official conviction records.We also tested whether substance use before the violent offense, adolescent excessive perceptions of threat, and a juvenile history of conduct disorder accounted for the link between mental disorders and violence.Results: Individuals meeting diagnostic criteria for alcohol dependence, marijuana dependence, and schizophrenia-spectrum disorder were 1.9 (95% confidence interval [CI], 1.0-3.5),3.8 (95% CI, 2.2-6.8), and 2.5 (95% CI, 1.1-5.7)times, respectively, more likely than con-

Mental Disorders and Violence in a Total Birth Cohort