Dr Charles Guest has worked in government and academic public health in Australia and elsewhere, following graduation from Melbourne, Deakin and Harvard Universities. After medical registration in 1980 and clinical practice in Melbourne, he joined the Epidemic Intelligence Service, Centers for Disease Control and Prevention, posted to the New York City Department of Health in 1984. Subsequently, he undertook research on chronic disease in Australian Aborigines, communicable disease and environmental health. He is currently a Senior Specialist in Population Health, Australian Capital Territory Government, and Adjunct Professor in the College of Medicine, Biology and Environment, Australian National University.; Professor Walter Ricciardi is the Director of the Institute of Hygiene, Universita Cattolica del Sacro Cuore, Rome. He graduated from the University of Naples (Medicine and Surgery) in 1984, specialised in Hygiene and Preventive Medicine in 1988 and obtained his MSc (Community Medicine) at the London School of Hygiene and Tropical Medicine in 1989. Since 1993 he has held a number of key positions including President of the European Public Health Association, and has undertaken work with the World Health Organisation and the European Union. He is a Fellow of the Faculty of Public Health Medicine, Royal Colleges of Physicians of the United Kingdom and is a Member of the National Board of Medical Examiners, USA. ; Dr Ichiro Kawachi is Professor of Social Epidemiology, and Chairman of the Department of Society, Human Development and Health, at the Harvard School of Public Health. Kawachi received his medical degree and Ph.D. (epidemiology) from the University of Otago, New Zealand. He is the author of over 400 articles on the social and economic determinants of population health. He was the co-editor (with Lisa Berkman) of the first textbook on Social Epidemiology, published by Oxford University Press in 2000. He is also Senior Editor of the Social Epidemiology section of the international journal Social Science & Medicine. He has served as an advisor to the WHO, the World Bank, and the Pan American Health Organization. ; Dr Iain Lang, Consultant in Public Health, NHS Devon & Senior Lecturer in Public Health, National Institute for Health Research Collaboration for Applied Health Research and Care for the South West Peninsula (NIHR PenCLAHRC), University of Exeter Medical School, Exeter, UK