Following the recent economic downturn, the religious roots of American corrections have begun to repopularize. While faith-based correctional interventions are common, there is very little known about their effectiveness with offender populations. Drawn from 15 studies, 57 effect sizes were calculated to estimate the average impact of religious prison programming on inmate attitudes and disciplinary infractions. Producing a weighted mean effect size of −.23 (g = −0.45 for attitudinal adjustments, g = −0.15 for institutional misconduct), the results indicate that religious interventions produce a modest but significant alteration to offender values and behaviors.