Many models have been proposed to explain both the rapidity of China's fertility decline after the 1960s and the differential timing of the decline in different places. In particular, scholars argue over whether deliberate policies of fertility control, institutional changes, or general modernization factors contribute most to changes in fertility behavior. Here the authors adopt an ethnographically grounded behavioral-institutional approach to analyze qualitative and quantitative data from three different rural settings: Xiaoshan County in Zhejiang (East China), Ci County in Hebei, (North China), and Yingde County in Guangdong (South China). The authors show that no one set of factors explain differential timing by a combination of differences in social-cultural environments (e.g. spread of education, reproductive ideologies, and gender relations) and politico-economic conditions (e.g. economic development, birth planning campaigns, and collective systems of labor organization) during the early phases of the fertility decline.