Concerns over rising prison and jail populations has spurred policymakers into increasing access to substance abuse treatment for offenders with drug-related charges. Such treatment programs can contribute to the criminal justice mandate by reducing offending among drug-involved offenders. The current study used multiple measures of recidivism to evaluate the effects of a highly coercive, long-term residential therapeutic treatment community in reducing recidivism among repeat felony drug offenders who, if not enrolled in the program, would be facing mandatory incarceration in State prison; charges are dismissed for participants who complete the program. A longitudinal quasi-experimental design was used that included an experimental sample of 150 offenders diverted to the Drug Treatment Alternative to Prison (DTAP) program and a control group of 130 offenders matched on arrest charges, prior felony convictions, age, race, gender, drug use, and desire for drug treatment. Study participants underwent extensive interviewing and completed standardized assessments; recidivism information was drawn from the New York City Criminal Justice Agency database. Results indicated that DTAP participants showed reductions in the prevalence and annual rate of recidivism, as well as delayed time to first rearrest compared with the control group. These results remained significant after controlling for criminal history and other covariates. The findings thus suggest that long-term, coercive therapeutic community treatment models can be effective at reducing recidivism among serious felony offenders. Tables, figure, notes, references