Ruud Koopmans is Director of the Migration, Integration, and Transnationalization research unit at the Wissenschaftszentrum für Sozialforschung Berlin and Professor of Sociology at the Vrije Universiteit Amsterdam. His research focuses on citizenship and immigration, European integration, social movements and collective action, and evolutionary sociology. He has authored and co-authored ten books, including Democracy from Below, New Social Movements in Western Europe, Challenging Immigration and Ethnic Relations Politics, and Contested Citizenship. He has published in leading journals such as the American Journal of Sociology, the American Sociological Review, the European Journal of Political Research, Evolution and Human Behavior, the Journal of Ethnic and Migration Studies, Mobilization, Social Problems, Theory and Society, and West European Politics. He is a member of the Scientific Advisory Councils of the Institute for German Studies and the Institute for Migration and Ethnic Studies, both in Amsterdam, and in 2004–2005 was an invited Fellow at the Center for Advanced Studies in the Behavioral Sciences at Stanford University. Paul Statham is Professor of Political Sociology and Director of EurPolCom, the International Research Network on European Political Communications, hosted by the Department of Sociology at the University of Bristol. He was formerly a Professor at the University of Leeds and a researcher at the Wissenschaftszentrum für Sozialforschung, Berlin. His research focuses on European integration and the public sphere and on multiculturalism, Islam, and migrants' political mobilization in Europe, within a cross-national comparative framework. He has published more than 20 articles in international scholarly journals, including the American Journal of Sociology, Western European Politics, the Journal of Common Market Studies, the Harvard Journal of Press/Politics, the European Journal of Communication, Ethnicities, Journalism, Mobilization, and the European Political Science Review. He is co-author of Contested Citizenship: Immigration and Cultural Diversity in Europe with Ruud Koopmans, Marco Giugni, and Florence Passy. He also co-edited Challenging Immigration and Ethnic Relations Politics. His research program has been supported by six major grant awards from the European Framework Programme and two from the British Economic and Social Research Council.