The article first updates previous reviews of cost-benefit analyses of correctional treatment programs (Welsh & Farrington, 2000a, 2000b). These reviews provide some evidence that correctional treatment is economically efficient in reducing reoffending when inmates are released back into the community. This has been determined through cost-benefit analyses that define the scope of the analysis, obtain estimates of program effects, estimate the monetary value of costs and benefits, calculate current value and assess profitability, describe the distribution of costs and benefits, and conduct sensitivity analyses. This article argues that if the monetary benefits of correctional treatment programs outweigh their costs, then efficiency requires increasing treatment resources for offenders. Further, linking treatment participation to an increased chance for parole could provide another incentive to participate in treatment. One of the studies reviewed in this article found that financial and job placement assistance for released offenders reduced theft offenses, increased ex-offender employment, and reduced reliance on social services such as welfare. These achievements translated into substantial monetary benefits for society. 1 table and 43 references