The monitoring of the population revealed a growing variance between projected and actual population. Major factors in this variance were a 4-percent decrease in fiscal 1984 admissions and an overestimate of the impact of the suspension of the meritorious-good-time policy. Revised projections are tracking well for 1985. The 10-year projection through 1994 is the output of a population simulation projection model developed by the Department of Corrections through a technical assistance grant. The model uses a Monte Carlo probability simulation technique to trace inmate cases through the corrections process by assigning probabilities to determine admissions, length of stay, and the inmate population. Probabilities are based on recent Illinois history (fiscal 1984 data) and analysis of current policies. This report also reviews recent criminal justice trends based on data obtained from police and court sources. These data place the prison population projections in context. 19 tables.