ANNA GATTI has been working for years as an economist at the World Health Organization in Geneva, Switzerland. Before this position, Dr Gatti had been Assistant Professor of Public Administration at Bocconi University, Milan, Italy, and Associate Professor of Organizational Behaviour at Trento University. She has held research positions at the Business School Fundacao Getulio Vargas, San Paolo, Brazil, and at the Goldman School of Public Policy, University of California, Berkeley. DEREK YACH is professor of Public Health and head of the Division of Global Health at Yale University, leader