“This bulletin examines the results of the Northwestern Juvenile Project-a prospective longitudinal study of youth detained at the Cook County Juvenile Temporary Detention Center in Chicago, IL. The authors discuss their findings on the prevalence of trauma and posttraumatic stress disorder (PTSD) among juvenile detainees and PTSD’s tendency to co-occur with other psychiatric disorders” (p. 1). Sections of this bulletin include: highlights; methods-measures; findings about trauma (overall rates, and specific trauma), posttraumatic stress disorder (PTSD), precipitating traumas, prevalence of trauma by gender and race/ethnicity, prevalence of comorbid psychiatric disorders among youth with and without PTSD, and prevalence of PTSD among youth with and without specific psychiatric disorders; discussion about trauma, posttraumatic stress disorder, comorbid disorders, and demographic characteristics; study limitations; directions for future research; and conclusion. Of the youth studied, 92.5% have had at least one traumatic experience, 84% have had more than one trauma, and have had 56.8% six or more events.