This special topic report examines the prevalence and characteristics of co-occurring substance abuse and mental health problems among juvenile detainees in Maricopa County. The findings come from the Co-occurring Disorder Addendum used during 2007. The findings reveal that almost 30 percent of juvenile detainees were at risk for a co-occurring disorder, and face significantly greater difficulties across a number of critical factors, including incarceration, homelessness, and victimization.