This study investigates the addition of a contingency management (CM) intervention to Veterans Health Administration substance use disorders treatment on during- and post-treatment outcomes for Veterans diagnosed with alcohol dependence only (n=191) or stimulant dependence (n=139). Participants were randomly assigned to 8weeks of usual care or usual care plus CM. Follow-up assessments occurred at 2, 6 and 12months. In the alcohol dependent subgroup, CM participants submitted significantly more negative samples (13 versus 11 samples, Cohen's d=0.54), were retained significantly longer (7 versus 6weeks, d=0.47), achieved significantly longer median durations of abstinence (16 versus 9 consecutive visits; median difference=7, 95% CI=4–8), and submitted significantly more negative samples at follow-ups (unstandardized effect size=0.669, se=0.2483) compared to usual care participants. Intervention effects were non-significant for the stimulant dependent subgroup. The study provides support for the effectiveness of CM interventions for alcohol dependent patients.