This is a study of the historical process by which an individual's identity as a rural or urban person became one of the most important sites of social difference in twentieth-century China. I focus on interaction between city and countryside to understand how the gap between the two realms grew, especially during the first three decades of the People's Republic of China (1949-1979). Attempts to cross the rural-urban divide reified difference. During the Mao Zedong era, the more city people attacked the rural-urban gap, the more alienated China's cities and countryside became from one another, and the more rigid urban and rural identities became.;I downgrade institutional explanations including the household registration (hukou) system in favor of social and cultural ones. In spite of restricted mobility, people continued to travel between city and countryside in massive numbers during the socialist period. Through rural-urban interaction, difference was negotiated on personal, familial, and professional levels. The hukou system was not a central factor in these moments of everyday contact. More important were language, appearance, labor, family, food, sex, and the historical legacies of the early twentieth century, when cities came to symbolize modernity and villages were equated with backwardness.;Previously untapped archival sources and oral history interviews allow for fresh perspectives on the Communist takeover of cities in 1949, the First Five-Year Plan, the Great Leap famine, the Four Cleanups movement, the sent-down youth program, and the Cultural Revolution. The leap and its aftermath poisoned the relationship between city and countryside. The leap's legacy helps to explain the Four Cleanups and Cultural Revolution, which further alienated villages from cities. Overall, the conclusions of the dissertation fall in between and add complexity to earlier views of the People's Republic as either a model of pro-rural development or as a starkly divided land of apartheid and oppression. Stories of everyday interactions in villages and neighborhoods, combined with new knowledge of how local officials made decisions, show a society that was more diverse, complicated, and above all, more human than the simple institutional division into urban and rural spheres would suggest.