OBJECTIVE: To examine the relationship between psychiatric disorders and violence in delinquent youth after detention. METHOD: The Northwestern Juvenile Project is a longitudinal study of youth from the Cook County Juvenile Temporary Detention Center (Chicago, Illinois). Violence and psychiatric disorders were assessed via self-report in 1,659 youth (56% African American, 28% Hispanic, 36% female, aged 13-25 years) interviewed up to 4 times between 3 and 5 years after detention. Using generalized estimating equations and logistic regression, we examined the following: the prevalence of violence 3 and 5 years after detention; the contemporaneous relationships between psychiatric disorders and violence as youth age; and whether the presence of a psychiatric disorder predicts subsequent violence. RESULTS: Rates of any violence decreased between 3 and 5 years after detention, from 35% to 21% (males), and from 20% to 17% (females). There was a contemporaneous relationship between disorder and violence. Compared to the group with no disorder, males and females with any disorder had greater odds of any violence (adjusted odds ratio [AOR] = 3.0, 95% CI = 1.9-4.7, and AOR = 4.4, 95% CI = 3.0-6.3, respectively). All specific disorders were associated contemporaneously with violence, except for major depressive disorder/dysthymia among males. Substance use disorders predicted subsequent violence. Males with other drug use disorder and females with marijuana use disorder 3 years after detention had greater odds of any violence 2 years later (AOR = 3.4, 95% CI = 1.4-8.2, and AOR = 2.0, 95% CI = 1.1-3.8, respectively). CONCLUSION: Aside from substance use disorders, the psychiatric disorders studied may not be useful markers of subsequent violence. Violence assessment and reduction must be key components of ongoing psychiatric services for high-risk youth.