Cultural diversity and the difficulty in regulating it have gradually replaced the class war and Keynesian compromise as topics of discussion at the dawn of the twenty-first century. Meanwhile, we are experiencing a new division of labor between cities and the state regarding political, institutional and the procedural handling of ethnic minorities. This book underlines the various policies that have been elaborated by local authorities on the issue of ethnic minorities by using a comparison between North America (Canada and United States) and Western Europe (France, Germany, Great Britain). If this study tends to emphasize the communities that result from immigration, it also takes into consideration that these findings may also concern other political minorities that, in very different institutional contexts, have begun to exert pressure in an effort to gain greater access to political systems and use cultural diversity as a rallying point and as a legitimate reason for action in liberal democracies.