Quanbao Jiang is Professor of Demography at the Institute of Population and Development Studies, Xi'an Jiaotong University, China. He has published extensively on gender imbalance, low fertility, aging, and health in China. Shuzhuo Li is University Distinguished Professor at Xi'an Jiaotong University, China, Vice President of the China Population Association, and a member of the Social Science Committee of the Ministry of Education. His research interests include population and development policies in China.