* We thank Martin Feldstein, Justin Lin, John Strauss, Zhixiong Zeng, and participants of seminars in the International Food Policy Research Institute, Nankai University, Peking University, and the University of Wisconsin-Madison, for their helpful comments. Mengtao Gao, Shuna Wang, and Shenwei Zhang provided superb research assistance. The Research Center of Rural Economy, the Ministry of Agriculture, the People’s Republic of China provided assistance in data collection. Financial supports from the Chinese Medical Board, the World Bank, and the National 211 Project of China are greatly appreciated. Corresponding author: Yang Yao, China Center for Economic Research, Peking University. Phone: 86-10-6275-3103; fax: 86-10-6275-1474; email: yyao@ccer.pku.edu.cn.