[영문]This paper studies the uninsured as a vulnerable population. We contend that reducing the size of the uninsured population yields important spillover benefits to the insured population, benefits that go beyond a lower charity care burden. Evidence presented in this paper reinforces studies in the literature that show that problems of health services quality and access facing insured people increase when the proportion of uninsured people in their local communities is greater. The size of such spillover benefits is reduced if the local market is large enough to be segmented based on insurance status.