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 11th century China. I map politicians’ kinship networks using their tomb epitaphs and collect data on their political allegiances from archival materials. 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 understand state building in China – a useful, yet understudied, counterpoint to the Euro-centric literature.