The prevalence of psychiatric disorders among incarcerated juveniles in Mississippi was examined. A total of 482 adolescents completed a diagnostic questionnaire and a subset (N = 317) was assessed with face-to-face semistructured interview. Most of the study participants met criteria for one mental disorder, 71?85% depending on assessment method, one-third have co-occurring mental health and substance abuse disorders. Gender and placement site differences in rates of some psychiatric disorders were also noted. Routine mental health screening should be performed on all juveniles placed in secure detention facilities to identify those who need treatment services.