This Chapin Hall report describes findings on the extent of system involvement among Illinois youth released from correctional facilities, tracking a population of youth under age 18 in Illinois following their release. Using administrative records, researchers develop profiles of reentry experiences across the many systems that serve youth and their families. Researchers examined their involvement with school, public assistance, foster care, and government-assisted services for health, mental health, and substance abuse needs. Because involvement in multiple services as part of the reentry experience is likely to impact the chances of reoffending, this body of information will be valuable to policymakers and practitioners. Five appendixes are included: (1) Description of Agency Data Sources; (2) Description of Health-Related Service Measures; (3) Technical Description of Latent Class Analyses; (4) Descriptive Statistics of Covariates in Multivariate Regression Analyses; and (5) Technical Description of Multilevel Regression Analyses. (Contains 15 footnotes, 4 figures, and 17 tables.) [This project was supported by the Illinois Criminal Justice Information Authority.]