The relationships between abstinence social support, substance use, and abstinence self-efficacy were examined among a sample of ex-prisoners exiting inpatient treatment for substance use disorders. Ordinary least squares regressions and bootstrapping procedure were used to test whether the relationship between abstinence social support and substance use would be mediated by abstinence self-efficacy. Significant relationships between variables were observed, and abstinence self-efficacy mediated the relationship between abstinence social support and substance use. Findings suggest that abstinence social support is enhanced by abstinence self-efficacy, and that these recovery resources can benefit persons with incarceration histories who have substance use disorders.