The tragic events of 11 September and the present military escalation in the Middle-East not only perpetrate, once again, painful questions of international politics, but underscore also the urgency in the contemporary political agenda for the necessity of a confrontation on topics of international relations and multicultural society. Is the cohabitation between different cultures possible within a democratic society? Can we harmonize different races and ethnic groups with the ideal of the state as a nation-descent? The formation of communities of immigrants based on a strict religious or ethnic principle does not incur into the risk of producing isolated groups adverse to the liberal principles and the views of civilitas of the western world? The intellectual contributions of this volume try to propose an answer to these questions, disproving the prevalent collective orientations that have been too often influenced by the theory of the “clash of civilizations”. Through a multidisciplinary perspective and a detailed examination of the theoretical and empirical aspects of the problem, emerges how multiculturalism is not to be understood as an element of corruption of the social solidarity, but rather as an alternative of defining the meaning of social integration and national membership. In the genuine perspective of multiculturalism, the value of what it means being Italians, French, Germans, British, is radically reformulated in order to obtain a post-national value. The concept of national identity departs from its original meaning of group-descent and becomes an ethnic and cultural “open” national identity. Also the community, far from fragmenting society in several separated parts, plays an important role of mediation/inclusion between the group of immigrants and the hosting society. Nowadays too often there is the tendency of considering claims for identity of the Islamic communities in Europe uniquely as expression of an extreme politicisation, a revival of the religious fundamentalism within the fortresses of the western secular tradition. Against these and others oversimplifications, the perspective of the multiculturalism and of the community offered in the different essays aims to underline how also in the case of Islam the claims for identity gain the meaning of a request of integration and access to modernity denied so far. Sociology and Political Philosophy engage themselves into a borderline debate that implies the redefinition and criticism of many concepts – from the concept of the State-Nation to the partial homogeneity of the beliefs and values it contains -, until the definition of a future where the harmonization of the differences will constitute an inevitable element of the daily life in our countries. This point will be here discussed by prominent scholars of the level of Boudon, Searle, Wieviorka, Kymlicka, Modood, Talbi, Maffettone, since for several years they have been engaged in discussing a topic upon which an accurate reflection seems to be required given the many instrumental simplifications that very often journalism has advanced.