Background - Many, if not most, incarcerated offenders have substance abuse problems. Without effective treatment, these substance-abusing offenders are likely to persist in non-drug offending. The period of incarceration offers an opportunity to intervene in the cycle of drug abuse and crime. Although many types of incarceration-based drug treatment programs are available (e.g., therapeutic communities and group counseling), the effectiveness of these programs is unclear.

Objectives - The objective of this research synthesis is to systematically review quasi-experimental and experimental (RCT) evaluations of the effectiveness of incarceration-based drug treatment programs in reducing post-release recidivism and drug relapse. A secondary objective of this synthesis is to examine variation in effectiveness by programmatic, sample, and methodological features. In this update of the original 2006 review (see Mitchell, Wilson, and MacKenzie, 2006), studies made available since the original review were included in an effort to keep current with emerging research.

Main results - Seventy-four evaluations met our eligibility criteria. The overall average effect of these programs was approximately a 15 to 17% reduction in recidivism and drug relapse. The effectiveness of such programs, however, varied by program type. Therapeutic communities had relatively consistent but modest reductions in recidivism and drug relapse. Counseling and narcotic maintenance programs had mixed effects. Specifically, counseling programs on average reduced recidivism but not drug relapse, narcotic maintenance programs had sizeable reductions in drug relapse but not recidivism, and boot camps had negligible effects on both recidivism and drug relapse.

Conclusions - This synthesis of evaluations of incarceration-based drug treatment programs found that such programs are modestly effective in reducing recidivism. These findings most strongly support the effectiveness of therapeutic communities, as these programs produced relatively consistent reductions in recidivism and drug use. Both counseling and incarceration-based narcotic maintenance programs had mixed effects. Counseling programs were associated with reductions in recidivism but not drug use; whereas, incarceration-based narcotic maintenance programs were associated with reductions in drug use but not recidivism. Note that our findings regarding the effectiveness of incarceration-based narcotic maintenance programs differ from a larger review of community-based narcotic maintenance programs (see Egli, Pina, Christensen, Aebi, and Killias, 2009). Finally, boot camp programs for drug offenders had negligible effects on both recidivism and drug use.