This study investigated matching client attributes to different aftercare treatments. A naturalistic sample of adults entering substance abuse treatment was randomized into either Structured Relapse Prevention (RP, n=61) or a 12-Step Facilitation (TSF, n=72) aftercare program. Four patient attributes were matched to treatment: age, gender, substance abuse profile, and psychological status. Substance use outcomes were assessed 3 and 6 months posttreatment. At 6 months, four significant matches were uncovered. Females and individuals with a multiple substance abuse profile reported better alcohol outcomes with TSF aftercare than their cohorts exposed to RP aftercare. Individuals with high psychological distress at treatment entry were able to maintain longer periods of posttreatment abstinence with TSF aftercare compared to their cohorts exposed to RP. Inversely, RP was found to maintain abstinence significantly longer for individuals reporting low distress compared to those with high distress. Finally, better outcomes were achieved when random assignment to aftercare was consistent with participant preference. Overall, an Alcoholics Anonymous approach to aftercare appears to provide the most favorable substance use outcomes for most groups of substance abusers. RP may be most suitable for clients whose psychological distress is low, especially where maintenance of abstinence is targeted. Where choice in aftercare program is possible, matching client preference with type of aftercare program can improve outcome.