ABSTRACT. This study tested the effectiveness of a therapeutic community (TC) intervention on imprisoned Korean substance abusers. Volunteer participants from 2 Korean prisons were randomly assigned to either the experimental group (n = 24) with the TC intervention or a control group (n = 24) with optional supportive sessions. Pretest and posttest data were collected on measures of abstinence self-efficacy and problem-solving skills. Participants in the TC intervention showed significant increases in abstinence self-efficacy and problem-solving skills, whereas those in the control group did not. The differences in abstinence self-efficacy for the TC were found for 2 of 3 subscales: Problem-Solving Confidence and Approach-Avoidance Style but not Self-Control. Further study is needed to replicate these findings with larger Korean prison populations and to establish the relationship between these skill dimensions and subsequent drug use and criminal recidivism for this population. Nevertheless, the findings suggest potential benefits of using a TC intervention with imprisoned Korean substance abusers.