In many developing countries, low population density may be a major reason for low school participation in rural areas, and the problem is likely to worsen with rapid urbanization. However, few studies have investigated empirically the role of population density in rural education, especially the moderating effect of population density on the outcomes of education policies. This study aims to fill this gap in the literature. From 1999 through the early 2000s, China launched a set of major nationwide policies aimed at universalizing 9-year compulsory education in rural areas. Using differencein- differences and triple difference strategies, we show that the policies significantly increased the probability of junior high school enrollment of rural children and, more importantly, these policies were more effective in densely populated regions. These fi ndings confi rm the importance of population density to rural education.