This article presents a theory of polity replication in which religious congregants prefer institutions in other realms of society, including the state, to be structured like their church. Polities, or systems of church governance and administration, generally take one of three forms: episcopal (hierarchical/centralized), presbyterian (collegial/regional), or congregational (autonomous/decentralized). When asked to cast a vote to shape institutions in a centralizing or decentralizing manner, voters are influenced by organizational values shaped by their respective religious traditions‘ polity structures. Past social scientific scholarship has neglected to explicitly connect religious affiliation, defined by polity, with members‘ stances on institutional design. However, previous examples of polity replication in action include the founding of the United States, the perpetuation of authoritarian regimes in Latin America, and the consolidation of the European Union. In this article, I provide original data on Roman Catholic and Southern Baptist support for city-county consolidation, an example of institutional design in metropolitan governance, in Louisville, Kentucky. Logistic regression results show that, other factors being equal, episcopal Catholics were 37 percent more likely to support consolidation in the 2000 referendum than were congregational Southern Baptists. Linear regression results show that Catholics were also more approving of the Louisville Metro government three years after its creation. In addition, Catholics who attend services more frequently were more supportive of consolidation and the consolidated regime. Perhaps owing to their polity structure, the effect of attendance for Baptists was unclear.