Most of the ancient walls surrounding China's cities have long since disintegrated, but invisible walls - legal restrictions separating the urban and rural populations - continue to contain urbanization. Kam Wing Chan examines how and why these bureaucratic 'walls' were built during the early days of socialism and why they remain during the current reform period. Dr Chan weaves together new empirical data and theory in this ground-breaking analysis of China's urbanization policies under socialism. He discredits the conventional wisdom that a low urban growth rate was the by-product of Mao's 'rural-biased' policies and points instead to long-term government efforts to promote industrialization while containing urban costs. In the post-Mao era city 'walls' have only been strengthened, as the government limits the costs of urbanization by refusing state-subsidized benefits to many of the cities' new migrants. Dr Chan critiques this policy and looks ahead to predict the impact of economic growth on urban demographics in the next century.