This study uses large, longitudinal, multisector administrative datasets of families investigated by child welfare services for maltreatment to explore which children are more likely to later enter psychiatric residential treatment facilities. This question is grounded in a pressing interest to understand these costly, highly restrictive mental health treatment settings. We use statewide data from one Southeastern state linked from multiple systems (child welfare services, income maintenance, and Medicaid). We use Cox regression analyses to develop models predicting psychiatric residential treatment facilities entry among children 5-17 years, whose families were investigated for maltreatment between 2003 and 2012 (n = 182,676). Findings show children from these families who enter foster care have a heightened risk for psychiatric residential treatment facilities entry (hazard ratio = 11.63), after controlling for other factors. Study findings build on a body of research underscoring the importance of the overlap of child welfare and mental health systems to child well-being.