This study examined six-month outcomes for 194 criminal justice clients exiting outpatient drug-free treatment and assigned to aftercare or standard treatment. It compared sub-samples of those achieving positive (n=111) and negative outcomes (n=59), as defined by drug and alcohol use and arrests. Psychological variables and attendance at religious services distinguished significantly between groups. Predictor variables developed from that comparison were employed in logistic regression analyses making use of the full sample. Aftercare was found to be particularly significant for reduction in drug use, with optimism/pessimism about one's future and religious observance also significant predictors for substance use.