Since the migration movements from Islamic countries, a Muslim diaspora has developed in many Western societies. While in classical Islamic theology residence in non-Muslim countries has always been a controversial issue, in the course of globalization and internationalization processes the classical distinction between "Islamic world" and "non-Islamic world" has been put into perspective. Now nearly 30 million Muslims live in Europe. The book offers an overview over Muslim communities in Europe, their history, present issues, and future challenges.