To better capture the varied institutions, programs, and policies associated with a thicker description of democracy, we use mixed-methods research to evaluate connections between local participatory institutions, federal social programs, local state capacity, and outcomes associated with well-being. Our complementary, mixed-methods research provides a thorough evaluation of the connections between democratic performance and well-being. Our quantitative analysis identifies general relationships within data covering an unusually large number of observations at a remarkably granular level. These trends lay the foundation for qualitative work, which unpacks the local, specific causal mechanisms driving relationships between democracy and well-being across Brazil. Our research thus leverages very rich data, considerable variation across Brazil’s municipalities, and decades of in-country experience among the coauthors to build theory and test hypotheses in ways that would be impossible in other contexts. The result is thorough analysis that improves our understanding of democracy and human development in Brazil, and a platform to improve local democratic performance around the world.