When are decentralized public institutions most likely to succeed in promoting effective public good provision? Two influential literatures in political science, those on “empowered participatory governance” and on “market-preserving federalism,” both emphasize that getting the rules right is the decisive factor in determining the success of these devolved institutions. An emphasis on institutional rules obscures the fact that the predatory politicians and adversarial organizations that the two literatures design rules to contain are also two factors that are most likely to influence the success or failure of these institutions. Through an examination of recent French and Italian experiments in decentralized collaborative governance, this article argues that the social capacities of secondary associations and the ties between local and central politicians are in fact the principal determinants of how well decentralized institutions deliver public goods.