Previous research suggested that community-level mental health service use was low following the World Trade Center Disaster (WTCD) and that brief interventions were effective. In the current study, we assess service use during a longer follow-up period and compare the effectiveness of brief versus multisession interventions. To assess these, we conducted baseline diagnostic interviews among New York City residents 1 year after the WTCD (N = 2368) and follow-up interviews 2 years afterward (N = 1681). At follow-up, there was an increase in mental health utilization, especially for psychotropic medication use, and a decrease in use of physicians for mental health treatment. The best predictor of service use at follow-up was higher WTCD exposure. Using propensity score matching to control for selection bias, brief mental health interventions appeared more effective than multisession interventions. These intervention findings held even after matching on demographic, stress exposure, mental health history, treatment history, access to care, other key variables. Our study suggested that community-level mental health service use increased in the follow-up period and that brief interventions were more effective than conventional multisession interventions. Since this study was designed to assess treatment outcomes, our findings raise clinical questions.