Factor mobility plays an important role in the convergence of regional income levels. This paper examines the role of labor mobility in China's regional economic development in the context of phases of demographic transition and the existence of institutional barriers. Our findings show that the two most important sources of interregional income disparity are per worker capital stock and technology level. The fact that the richest provincial economies are at the later phase of demographic transition provides a major reason for why those economies have accumulated higher per worker capital stock and achieved higher productivity levels. We also discover that regional per capita income levels have not displayed convergence since the mid 1990s. Two observations explain this phenomenon. One observation is that capital and labor movements have played only a limited role in equalizing their marginal returns across regions despite the fact that labor mobility has substantially strengthened this role since 2000. The other observation is that the impact of demographic changes on income growth has been distinctly uneven between the rich and poor regions. This phenomenon can be attributed to some particular features of China's interregional labor migration. (c) 2009 The Earth Institute at Columbia University and the Massachusetts Institute of Technology.