Masahisa Fujita, a member of the Japan Academy and the President of the Research Institute of Economy, Trade and Industry, has been a major contributor to spatial economic theory during his twenty-year tenure at the University of Pennsylvania and more recently at Kyoto University and Konan University. Professor Fujita is the author or co-author of three books: Spatial Development Planning (1978); Urban Economic Theory (Cambridge, 1989), which remains to this day the most authoritative graduate textbook on urban economics; and The Spatial Economy (1999, co-authored with Paul Krugman and A. J. Venables), which defines the field of new economic geography. Jacques-François Thisse, a fellow of the Econometric Society and of the Regional Science Association International, is Professor of Economics at the Université Catholique de Louvain (Belgium) and the Higher School of Economics (Russia). He has published in numerous journals, including the American Economic Review, Econometrica, the Journal of Political Economy, the International Economic Review, Management Science, Exploration in Economic History, and the Journal of Economic Geography. He is the co-author of Discrete Choice Theory of Product Differentiation, Economic Geography, and Economic Geography and the Unequal Development of Regions. Professors Fujita and Thisse co-authored the first edition of Economics of Agglomeration: Cities, Industrial Location, and Regional Growth (Cambridge, 2002).