Part I, "Impact on Population," addresses the important factors that underlie the increasing prison population in Illinois and why this trend is expected to continue. Increases in the murder and class X and 1 populations that have resulted from determinate sentencing are evident. The impact of life, death, and sexually-dangerous-person sentences on the inmate population can also be seen. The changing habitual-offender, habitual-child- sex-offender, and guilty-but-mentally-ill populations are presented as well. Part II, "Length of Stay," notes the time inmates are serving in prison. In addition, the pace of releasing inmates sentenced under indeterminate sentencing is shown. The impact of the abolition of the forced release and misdemeanor admission policies are also shown. Part III, "Sentences Imposed," provides the data for sentencing patterns since 1978. Data for determinate and indeterminate sentences, along with life, death, and sexually-dangerous-person sentences are provided as well. The number of extended and shortened sentences are reported by offense. Median sentences for the major offenses are provided by judicial circuit and district and geographic region. 49 tables, 16 figures, and appended sentencing-practices comparison, along with definitions and data interpretation guidelines.