Lead time—the duration of construction and commissioning—is an important determinant of the capital cost of nuclear power plants (NPPs). For an industry dominated by a handful of multinational firms, the degree of cross-national variation is surprising. NPP lead times have historically trended upward over time in Western nations, and yet they are comparatively quick and stable in East Asia. I theorize that the institutional capacity and autonomy of subnational governments can partially explain these patterns in the data. Having assembled a novel data set on the design specifications of the global population of NPPs, I empirically document a positive association between political decentralization and NPP lead time that is not explained by observed cross-country differences in NPP design. The results are suggestive of the hypothesis that political decentralization creates conditions that slow NPP construction for nontechnical reasons. However, the findings are not robust to certain robustness checks and fail to rule out the possibility that unobserved differences in design explain this association.