The study found that 54 percent of Hawaii's prisoners were incarcerated in private prisons on the mainland, the highest percentage among all U.S. States with prisoners incarcerated out-of State. At the end of 2009, it cost approximately $119 per day to incarcerate an inmate in Hawaii compared to approximately $62 per day to incarcerate a prisoner in a private prison on the mainland; however, the latter cost estimate is not all-inclusive. Seventy-five percent of those paroled in fiscal year 2006 never served time in a private prison on the mainland; of the 25 percent incarcerated on the mainland, 70 percent served half or more of their time there. The mainland cohort included substantially more men than did the Hawaii cohort. Just over half of parolees in both cohorts failed on parole within 3 years. The average time to recidivism in both cohorts was about 15 months. The recidivism rate for the mainland cohort (53 percent) was slightly lower than the recidivism rate for the Hawaii cohort (56 percent). There was more recidivism among the mainland cohort for violating parole conditions. In both cohorts, older parolees recidivated less than did younger parolees. Since there is no empirical justification for the policy argument that private prisons reduce recidivism better than public prisons, Hawaii should decide whether to continue, discontinue, expand, or reduce reliance on private prisons based on other criteria. Extensive tabular and graphic data and 100 references