This study examines the prevalence of psychiatric disorders among juvenile detainees in Cook County, Illinois, using a stratified random sample of 1,829 African American, non-Hispanic white, and Hispanic youth. The Diagnostic Interview Schedule for Children (DISC 2.3) was used to assess the presence of various disorders over the past six months. The results show that nearly two-thirds of males and nearly three-quarters of females met diagnostic criteria for one or more psychiatric disorders. Substance use disorders and disruptive behavior disorders were the most common, with half of males and almost half of females meeting criteria for substance use disorders, and over 40% of both genders meeting criteria for disruptive behavior disorders. Affective disorders were also prevalent, especially among females, with 20% of females meeting criteria for a major depressive episode. Rates of many disorders were higher among females, non-Hispanic whites, and older adolescents. The study highlights the substantial psychiatric morbidity among juvenile detainees, which poses a challenge for the juvenile justice system and the mental health system after release. The findings suggest that the juvenile justice system may be an important entry point for addressing mental health issues in this population.This study examines the prevalence of psychiatric disorders among juvenile detainees in Cook County, Illinois, using a stratified random sample of 1,829 African American, non-Hispanic white, and Hispanic youth. The Diagnostic Interview Schedule for Children (DISC 2.3) was used to assess the presence of various disorders over the past six months. The results show that nearly two-thirds of males and nearly three-quarters of females met diagnostic criteria for one or more psychiatric disorders. Substance use disorders and disruptive behavior disorders were the most common, with half of males and almost half of females meeting criteria for substance use disorders, and over 40% of both genders meeting criteria for disruptive behavior disorders. Affective disorders were also prevalent, especially among females, with 20% of females meeting criteria for a major depressive episode. Rates of many disorders were higher among females, non-Hispanic whites, and older adolescents. The study highlights the substantial psychiatric morbidity among juvenile detainees, which poses a challenge for the juvenile justice system and the mental health system after release. The findings suggest that the juvenile justice system may be an important entry point for addressing mental health issues in this population.