The findings indicated that ISUs had a positive effect on offender institutional behavior and early release opportunities. Results revealed the rate of seizure of substance-related contraband was lower for the ISUs during the study period than for the non-ISUs. In 7 of the 11 months under examination, no substance-related contraband was found during searches of ISUs. Results of random drug testing indicated a decline in drug use detection from 15 percent prior to ISU admission to 3 percent following ISU admission. Staff and offenders reported that drugs and alcohol were less available in the ISUs than they were in other areas of the institution. Offenders in ISUs had lower rates of misconduct than other offenders and 62 percent of ISU residents received a discretionary release compared to 46 percent of a matched comparison group. Only 25 percent of ISU residents were returned to custody following release compared to 39 percent of the comparison group. The cost savings related to decreased incarceration time averaged approximately $8,000 per ISU resident. The findings suggest that the Correctional Service of Canada should consider expanding the use of ISUs. The evaluation involved 246 male offenders who were admitted to 1 of 5 ISU pilot sites over an 11-month period between September 2000 and July 2001. ISUs are specialized and voluntary living areas within Federal penitentiaries that are designed to more effectively address offenders' alcohol and drug problems. Data were drawn from a battery of assessments that all offenders completed at admission and discharge, as well as monthly behavioral checklists, institutional misconduct information, search and seizure data, and results of drug testing. Offenders were followed for between 8 and 24 months following the study period. Matched comparison groups were used to evaluate the results. 3 figures, 5 notes