Martin Feldstein is the George F. Baker Professor of Economics at Harvard University and president and CEO of the National Bureau of Economic Research. He is the author and editor of many books, including International Capital Flows and Privatizing Social Security, both published by the University of Chicago Press. Horst Siebert is president of the Kiel Institute of World Economics, professor of economics at the University of Kiel in Germany, and member of the German Council of Economic Advisers.