Agriculture has made major contributions to China's economic growth and poverty reduction, but the literature has rarely focused on the institutional factors that might underpin such structural transformation and productivity. This paper aims to fill that gap. Drawing on an 8-year panel of 1,200 households in six key provinces, it explores the impact of government land reallocations and formal land-use certificates on agricultural productivity growth, as well as the likelihood of households to exit from agriculture or send family members to the non-farm sector. It finds that land tenure insecurity, measured by the history of past land reallocations, discourages households from quitting agriculture. The recognition of land rights through formal certificates encourages the temporary migration of rural labor. Both factors have a large impact on productivity (at about 30 percent each), mainly by encouraging market-based land transfers. A sustained increase in non-agricultural opportunities will likely reinforce the importance of secure land tenure, which is a precondition for successful structural transformation and continued economic attractiveness of rural areas.