This article explores a neglected topic in the social welfare, poverty, and demographic literatures—the link between population density and welfare participation in the United States. Longitudinal data from the Panel Study of Income Dynamics are used to meet two objectives: first, to test whether a relationship exists between population density and use of the food stamp program among eligible households; second, to explore the potential reasons for such a relationship. Our findings show that population density has a strong, positive impact on the likelihood of participating in the food stamp program. Low-income respondents in urban areas are significantly more likely to use food stamps in both an aggregate and a multivariate context. In analyzing the dynamic underlying such an effect, we find that those in urban areas are more likely to possess accurate eligibility information and to hold less adverse attitudes toward the use of welfare. These factors in turn increase the likelihood of food stamp participation.