In 2000, the Illinois Probation Outcome Study was conducted by the Illinois Supreme Court’s Administrative Office of the Illinois Courts to fill the gap in information about Illinois’ juvenile probation population, and the effectiveness of probation. Data were collected and analyzed from a sample of more than 820 juvenile probationers discharged during 2000. The study examined demographic and family characteristics, economic, educational, and family income, substance abuse history and prior involvement in the juvenile or criminal justice system, and history of psychiatric treatment. Several probation outcome dimensions were examined and included: legal discharge status, technical violations, new arrests, results of urinalysis, compliance with conditions of treatment, and changes and stability in juvenile probationers’ lives. The data illustrate the complex nature of the probation caseloads in Illinois, as well as the broad array of requirements juvenile probationers and those involved in supervision are responsible for. The Illinois’ probation system is working with a population that has considerable risk factors, ranging from low-educational achievement, substance abuse problems, and prior involvement in the system. In addition, the population increased during the 1990's. The outcomes of juvenile probation sentences in Illinois are very positive, with slightly more than one-third of juvenile probationers rearrested for a new offense while on probation and with few violent in nature. When assessing the impact and effectiveness of probation in Illinois, overall, 70 percent of those ordered to treatment either completed it or were still enrolled by the end of probation. References and appendixes 1-3