William D. Nordhaus is Sterling Professor of Economics at Yale University, New Haven, Connecticut, USA. He completed his undergraduate work at Yale University and received his Ph.D. in Economics in 1967 from the Massachusetts Institute of Technology, Cambridge, USA. He has been on the faculty of Yale University since 1967 and has been Full Professor of Economics since 1973. Professor Nordhaus lives in downtown New Haven with his wife Barbara, who works at the Yale Child Study Center. He is a member of the National Academy of Sciences and a Fellow of the American Academy of Arts and Sciences. He is on the research staff of the Cowles Foundation and of the National Bureau of Economic Research and has been a member and senior advisor of the Brookings Panel on Economic Activity, Washington, D.C. since 1972. Professor Nordhaus is current or past editor of several scientific journals and has served on the Executive Committees of the American Economic Association and the Eastern Economic Association. He serves on the Congressional Budget Office Panel of Economic Experts and was the first Chairman of the Advisory Committee for the Bureau of Economic Analysis.