CONTRIBUTORS ALESSANDRA CASELLA is professor of economics at Columbia University and directeur d’études at l’École des Hautes Études en Sciences Sociales. JAMES E. RAUCH is professor of economics at the University of California, San Diego, and research associate at the National Bureau of Economic Research. RONALD S. BURT is the Hobart W. Williams Professor of Sociology and Strategy at the University of Chicago Graduate School of Business, the Shell Professor of Human Resources at the Institut Européen d’Administration d’Affaires (INSEAD) in Fontainebleau, France, and director of Raytheon’s Leadership Institute. GREGORY BESHAROV is assistant professor of economics at Duke University. ROBERT C. FEENSTRA is a professor in the Department of Economics at the University of California, Davis, and a research associate of the National Bureau of Economic Research. NEIL FLIGSTEIN is the Class of 1939 Chancellor’s Professor in the Department of Sociology at the University of California, Berkeley. AVNER GREIF is Bowman Family Professor of Humanities and Sciences at Stanford University. GARY G. HAMILTON is professor of sociology and the Jackson School of International Studies at the University of Washington, Seattle. DENG-SHING HUANG is a research fellow in the Institute of Economics at Academia Sinica in Taipei, Taiwan. ALAN KIRMAN is professor of economics at GREQAM, University of Aix-Marseille, directeur d’études at l’École des Hautes Études en Sciences Sociales, and member of the Institut Universitaire de France. viii Contributors JOHN F. PADGETT is research professor at the Santa Fe Institute and associate professor of political science at the University of Chicago. REBECA RAIJMAN is assistant professor of sociology at Haifa University in Israel. JOEL SOBEL is professor of economics at the University of California, San Diego. MARTA TIENDA is Maurice P. During ’22 Professor of Demographic Studies, professor of sociology and public affairs, and director, Office of Population Research at Princeton University..