This article revisits government failure theory by examining the relationship between government decentralization and the size of the nonprofit sector (NPS). Government failure theory posits that nonprofits are most active in regions where the largest gap exists between the homogeneous supply of public service and heterogeneous citizen demands. Following this theory, government decentralization should decrease the size of the NPS, as it increases the efficiency and heterogeneity of government services. This article tests this hypothesis using a sample of U.S. counties. Decentralization is measured in two dimensions: vertical decentralization and horizontal fragmentation. After using instrumental regressions to eliminate the endogeneity bias, we find that counties with a more horizontally fragmented governmental system are associated with a larger NPS. Vertical centralization leads to a denser NPS but has no impact on the NPS revenue or assets. The impacts of resident heterogeneity are also mixed. As such, government failure theory is only partially supported, at best. Contrarily, interdependence theory is supported by this study.