This article investigates the influence of participation in and exposure to voluntary associations on fertility-limiting behavior. Its theoretical framework, drawn from the sociological literature on social networks and voluntary associations, the demographic literature on program participation, and the literature on health behavior, delineates the mechanisms through which participation in voluntary associations is likely to influence permanent contraceptive use. The article draws from three data sources to empirically test the framework: individual-level survey data from couples residing in the Chitwan Valley in south-central Nepal; data on the neighborhoods of the Chitwan Valley collected using an integrated application of ethnographic, survey, and archival methods; and the authors' own ethnographic interviews in these neighborhoods. Empirical analyses show that participation in a range of voluntary associations increases permanent contraceptive use. Furthermore, living in a neighborhood with a voluntary association increases permanent contraceptive use. Finally, participation in different types of voluntary associations – including credit groups, women's groups, agricultural groups, and youth groups – appears to be similarly related to permanent contraceptive use.