The right to education for children from rural migrant families in urban areas has sparked heated debates in China. While there are increasing indications of policy changes to bring public education to all citizens regardless of their residency, it is less clear what kinds of resources are needed to create an education supply to serve this constantly moving and ever-growing population. Using archival and interview data on a large urban district in Shanghai, the authors analyze the constraints faced by local government in providing full-scale free education to migrant children. The authors find that the public finance scheme, teacher staffing policy and land use policy are the three factors that constrain the supply of public education in large metropolitan areas. This analysis also shows that under the current decentralized management scheme, local government alone does not have the capacity to resolve these constraints. This finding calls for coordination among various state branches at the national level.