Fiscal federalism predicts local governments will avoid social welfare expenditures, owing to capital mobility across local jurisdictions. Yet Census of Governments data consistently show that many local governments provide one or more social welfare functions, and moreover many jurisdictions provide these functions without federal or state intergovernmental support. This article finds evidence that, while local expenditures are largely driven by fiscal capacity and federal and state assistance, local decisions on providing social welfare functions and participating in intergovernmental revenues are primarily affected by degree of capital mobility and by local political factors. Consequently, local governments exercise much greater autonomy over social welfare policymaking than fiscal federalism suggests.