The findings of a study determine whether social supplemental security income (SSI) or Social Security disability income (SSDI) disability payments is associated with increased drug and alcohol use in a sample of 6,199 homeless and mentally ill participants in the Access to Community Care and Effective Social Supports and Services. The authors report on the observational, 12-month, cohort study that was completed over 4 years. Substance abuse and other outcomes were compared between the participants who did not receive SSI or SSDI during the 12-month study, those newly awarded benefits, and those without benefits throughout the 12 months. The authors conclude that "in this vulnerable population, participants with newly awarded benefits did not have any different drug use changes than those without benefits, and had relatively more days housed. The hypothesis that Social Security benefits facilitate drug use was not supported by longitudinal data in this high-risk population. (Rosen, Mark. McMahon, Thomas. Lin, HaiQun. Rosenheck, Robert.)