The one-child policy in China, as the centerpiece of family planning policies, became fundamental national policy in the early 1980s. Over the past thirty years, this policy not only changed the course of China’s population but also has had a massive impact on the country’s economy and society. By now, China’s population has entered a phase of complex change. New demographic phenomena are appearing. Many demographic indicators are displaying change of a ‘turning point’ nature. How are these demographic changes going to affect China’s socioeconomic development? How are they going to affect people’s general welfare? Not only are these things of great concern to people, but also they are things that government policies must now address. The focus of this chapter is on the context for the decision to establish China’s one-child policy, and on the impact that policy has had. The chapter then sifts through the major demographic changes that have since resulted.