With the move to a market-oriented economy, the growth of large scale internal migration has created new forces for institutional change in China. By 2010, 260 million citizens were living outside of their permanent hukou (household registration) location, a major challenge to the constrictive Mao-era system of migration and settlement planning and the rigid intuitional division of rural and urban China. Jason Young shows how these new forces have been received by the state through analysis of major hukou reforms. He documents the dynamic process of institutional change and explains the ongoing importance of China's enduring hukou system to socioeconomic and political development in the world's largest developing country.