Somnath Chatterji currently leads the Surveys, Measurement and Analysis programme in the Department of Information, Evidence and Research at the World Health Organization (WHO). He coordinates WHO’s Study on Global Ageing and Adult Health (SAGE) supported by the National Institute on Aging (NIA), USA – a longitudinal study on ageing in six low and middle income countries. He has been a principal investigator in the Collaborative Research on Ageing in Europe (COURAGE) and is currently a lead investigator in the Ageing Trajectories of Health: Longitudinal Opportunities and Synergies (ATHLOS) and The Utility of omic-based biomarkers in characterizing older individuals at risk for frailty, its progression to disability and general consequences to health and well-being - The FRAILOMIC Initiative (FRAILOMIC), both funded by the European Commission. He has also been involved in the network on the Harmonization of Longitudinal Studies on Aging and the Biomarker Network supported by the NIA. The measurement of health, well-being and other health-related outcomes, their trends and determinants is the main focus of the international studies of the team. He also co-directs WHO’s World Mental Health surveys on the epidemiology of mental disorders in 30 countries. He led the Lancet Series on Ageing published in 2014 and was one of the key persons responsible for WHO’s World Report on Ageing and Health released in 2015.