Because ISP requires that participants serve a few months in prison, obey curfews, and perform community service, it provides a level of punishment intermediate between probation and ordinary prison and parole. An analysis of data for ISP participants and a matched sample of offenders sentenced to prison before ISP was instituted shows that ISP participants spent about 200 fewer days each in prison, saving 62,000 bed-days and approximately $7,000 to $8,000 per offender. Further, ISP participants' median gross yearly income was approximately $10,000 as compared to $5,000 for parolees. These higher earnings produced proportional increases in taxes and child support paid by ISP participants. Community service work by participants totaled about $200,000 per year (valued at minimum wage). ISP participants' recidivism rates at the end of 2 years was roughly 10 percentage points lower than that of the comparison group, although some of this reduction may be attributable to the selective screening component of ISP rather than to supervision and counseling components. Finally, an analysis of attitudes toward the severity of ISP and the program requirements suggest that it does serve as an intermediate form of punishment. 2 tables, 1 note, and 6 references. (Author abstract modified)