We use rich data from the Indonesia Family Life Survey to assess the relationship between mothers' access to social capital via participation in community activities and their children's health. We exploit the advantages of longitudinal data and community fixed effects to mitigate some of the concerns about spuriousness and reverse causality that predominate in this literature. We find that children from families with relatively low levels of human and financial capital fare better with respect to health status when their mothers are more active participants in community organizations. In fact, the association between maternal participation and child health is strong and positive only for children from relatively disadvantaged backgrounds, as measured by their mothers' educational and household economic resources. The results suggest that in poorer settings community involvement may benefit disadvantaged families, possibly by providing resources and information that would otherwise be inaccessible. (Contains 4 tables and 4 notes.)