Research data revealed the dramatic minority overrepresentation within the juvenile justice system in Illinois, it suggests little about why this phenomenon has occurred. African-American youth were overrepresented among youth arrested and committed to the Illinois Department of Corrections (IDOC). Specifically, the arrest representation index for Black youth was 3.14 compared to 0.65 for White youth. The relative rate index indicated that Black youth in Illinois were arrested at five times the rate at which White youth were arrested. Similar findings revealed that Black youth in Illinois were committed to the IDOC at five times the rate of White youths. State-level data also indicated that Hispanic youth were overrepresented among IDOC commitments, although to a lesser extent than were Black youth. Data were drawn from the United States Census Bureau, the Computerized Criminal History Information System (CHRI), and the IDOC. Data were drawn on the juvenile population in Illinois aged 12 to 17 years. Analytic measures included the calculations of an arrest representation index, which compared the percentage of all youth of a particular race with their percentage in the general juvenile population, as well as a relative rate index and a disproportionate representation index, all of which are described. Tables, figures