The China Health and Retirement Longitudinal Study (CHARLS) is a landmark survey of the middle-aged and elderly in China. Spearheaded by Peking University’s National School of Development, the study aims to collect multidisciplinary data, ranging from socio-economics status to health conditions, to be used to support the scientific analysis of China’s ageing issues. The Charls baseline study polls a nationally representative sample of more than 17,700 individuals from more than 10,000 households, in 150 counties/districts in 28 of China’s 30 provinces (excluding Tibet). The individuals will be followed up every two years.