Ac know ledg ments This work was born as a doctoral dissertation at the University of Milano, Italy. My fi rst and major debt of gratitude is to Paola Villa, my Ph.D. supervisor during the research. Her intellectual generosity and support have been very stimulating and encouraging. Earlene Craver, Axel Leijonhufvud, and Giorgio Fodor gave me fundamental advice during the outline phase of the research. Roger J. Sandilands shared with me opinions, literature, and advice on countless occasions, with openness and enthusiasm. I heartily thank him for his generosity and friendship. Within the World Bank, François Bourguignon, former chief economist and se nior vice president, Jean-Jacques Dethier, research manager, and Elisa Liberatori-Prati, chief archivist, supported my work, encouraged publication of this book in En glish and gave me valuable and inspiring comments. I also received useful comments and support from Biagio Bossone, Barbara