Introduction In recent decades, the People’s Republic of China and the Republic of Korea have experienced fertility transitions that are among the most rapid of any countries in the world. In 1960, both countries had total fertility rates of around 6 children per woman. By 2005, these had declined to 1.7 in China and to 1.1 in South Korea (Figure 5.1). In this chapter, we address empirically the impact of social and economic development on the fertility reductions in China and Korea. County level fertility data, for the year 2000 for the over 2,400 counties in China and for the year 2004 for the 231 counties of South Korea, are utilized to examine the extent to which the variation in fertility is accounted for by factors of socioeconomic development.