A long tradition in social sciences scholarship has established that kinship-based institutions undermine state building. I argue that kinship networks, when geographically dispersed, cross-cut local cleavages and align the incentives of self-interested elites in favor of building a strong state, which generates scale economies in providing protection and justice throughout a large territory. I evaluate this argument by examining elite preferences related to a state-building reform in eleventh century China. I map politicians’ kinship networks using their tomb epitaphs and collect data on their political allegiances from archival materials. A statistical analysis demonstrates that a politician’s support for state building increases with the geographic size of his kinship network, controlling for a number of individual, family, and regional characteristics. My findings highlight the importance of elite social structure in facilitating state development and help to advance our understanding of state building in China—a useful, yet understudied, counterpoint to the Eurocentric literature.