WHO SAGE is part of an ongoing program of work to compile comprehensive longitudinal information on the health and well-being of adult populations and the ageing process. The core SAGE collects data on adults aged 18+ years, with an emphasis on populations aged 50+ years, from nationally representative samples in six countries: China, Ghana, India, Mexico, Russian Federation and South Africa. Wave 1 total sample size is over 40,000 individuals. Wave 2 interviews were completed in 2014/15 in five countries. Wave 2 data will be released in the public domain end 2020. Wave 3 data was completed in March 2020.