This report from the National Center for Juvenile Justice constructs baseline measures of juvenile justice data and trends in Illinois. From these benchmarks, progress in juvenile justice system reform may be measured. The Illinois initiative, sponsored by the John D. and Catherine T. MacArthur Foundation, follows the Foundation’s ‘Model Systems Framework’, which focuses on these key system goals: 1) Incarceration reductions/Diversion increases; 2) Reductions in race disparities; 3) Reduction in transfers to the adult criminal system; 4) Reduction in recidivism; and 5) Increased participation in positive social activities. The report gives a summary of juvenile demographic trends; discusses various indicators that describe Illinois’ reliance on formal case handling and incarceration; analyzes evidence of race disparities; describes transfer trends; and discusses recidivism measures.