The Inmate Classification and Profile Analysis Subcommittee of the Special Joint Legislative Advisory Committee on Corrections was assigned the responsibility of identifying individual characteristics of the Illinois Department of Corrections inmate population. In addition to the presentation of demographic data for each correctional institution, the data analysis procedures used in the study are described, and the demographic variables are enumerated, with a composite inmate profile provided for each variable. The variables utilized for this study included age, race, ethnic preference, sex, division, veteran, prior commitments, marital status, occupational skill, crime class, class set, employment status, last grade completed, residency, minimum sentence, maximum sentence, and offense. A composite profile indicated that a majority of the population analyzed consisted of young, black, single, non-veteran males who residing in Cook County, who have not completed high school and were unemployed at the time of their arrest. Other analyses are conducted by crime class, offense, and sentence. The bulk of the report consists of individual institutional analyses and data profiles of the inmate population of each of the following Illinois correctional institutions: Statesville, Menard, Joliet, Vandalia, Sheridan, Dwight, Pontiac, Logan, Menard Psychiatric Correctional Center, and Vienna. Two appendices provide information on classification of offenses and ranges of felony sentences.