Robert A. Mundell, a Nobel Prize-winning economist whose theorizing opened the door to understanding the workings of global finance and the modern-day international economy, while his more iconoclastic views on economic policy fostered the creation of the euro and the adoption of the tax-cutting approach known as supply-side economics, died on Sunday April 4 2021 at his home, a Renaissance-era palazzo that he and his wife restored, near Siena, Italy. He was 88. Since 1974, Robert Mundell (born 1932) had been Professor of Economics at Columbia University in New York. After studying at M.I.T. and the London School of Economics, he received his Ph.D. from M.I.T. in 1956, and was the Post-Doctoral Fellow in Political Economy at the University of Chicago in 1956-57. He taught at Stanford University and The Johns Hopkins Bologna Center of Advanced International Studies before joining the staff of the International Monetary Fund in 1961. From 1966 to 1971 he was a Professor of Economics at the University of Chicago and Editor of the journal of Political Economy; and from 1965 to 1975, he was (summer) Professor of International Economics at the Graduate Institute of International Studies in Geneva, Switzerland. For 1997-98 he was the AGIP Professor of Economics at the Johns Hopkins Bologna Center of the Paul H. Nitze School of Advanced International Studies. Professor Mundell has been an adviser to a number of international agencies and organizations including the United Nations, the IMF, the World Bank, the European Commission, and several governments in Latin America and Europe, the Federal Reserve Board, the US Treasury and the Government of Canada. In 1970, he was a consultant to the Monetary Committee of the European Economic Commission, and in 1972-73 a member of its Study Group on Economic and Monetary Union in Europe. He was a member of the Bellagio-Princeton Study Group on International Monetary Reform from 1964 to 1978, and Chairman of the Santa Colombia Conferences on International Monetary Reform between 1971 and 1987. After his first marriage, in 1957, to Barbara Sheff ended in divorce in 1972, he married Valerie Natsios — whom he had started living with in 1984 — shortly after their son was born in 1997. In addition to his wife, he is survived by their son, Nicholas; a son, Bill, and a daughter, Robyn, from his first marriage; and eight grandchildren. Another son from his first marriage, Paul, was killed in a car accident in 2018.