Data provided by the Illinois Criminal Justice Authority were examined to estimate the proportion of juvenile and adult probationers in Illinois who received publicly funded drug or alcohol treatment between July 1, 1996, and June 30, 2000. Data sources included the 2000 Illinois Adult and Juvenile Probation Outcome Study, which sampled all adult and juvenile probationers discharged during 1 month in 2000. Data consist of information on probationers’ backgrounds, criminal histories, conditions of supervision, use of social services, and performance on probation. A second data source, the Illinois Drug and Alcohol Records Tracking System (DARTS), provided information on the recipients of state-subsidized drug treatment. Data analysis involved linking and matching the datasets on at least three variables. The matched samples contained 921 adult probationers and 112 juvenile probations; total samples included 3,364 adults and 821 juveniles. The matched and total samples were compared on gender, age, race, marital status, education, and income. Results of descriptive, bivariate, and logistic regression analysis indicate that within the overall sample, most adult probationers received between one and three publicly funded treatment services. Racial differences in drug use are reported as the analysis reveals that African-American and White probationers were more likely to receive larger numbers of treatment services than Hispanic probationers, due in part to their lower levels of reported drug use. In terms of gender differences, while women reported lower levels of substance abuse, they were more often diagnosed with severe dependence problems and received larger numbers of publicly funded treatment services than their male counterparts. Differences among probationers in type of offense, employment, marital status, and age are similarly explicated. Probation outcome analysis revealed that almost 40 percent of probationers were arrested while on probation and another 40 percent were discharged from probation unsuccessfully. Approximately 20 percent had their sentences revoked. The report next enumerates the findings from the juvenile samples, which indicate that females were more likely to receive a greater number of services and most juveniles, regardless of gender, had received three or fewer state-funded treatment services. Given the link between drug use and probation failure, future research should focus on identifying resources to meet the drug treatment demand.