Researchers in organizational ecology have long been interested in identifying the factors associated with organizations closing their doors. Though the predictors of closure have been examined across many different types of organizations, private substance abuse treatment centers, often characterized as unstable and having high closure rates, have not been subject to empirical study. Data for this study were derived from a nationally representative longitudinal study of 450 private substance abuse treatment centers. Contrary to most previous research, center age was not a significant predictor of closure. Significant predictors included center capacity, being a freestanding facility, the percentage of clients covered by Medicaid, and the ratio of patients to full-time equivalents.