This book compares how different Islamic communities assert their authority to represent "True Islam" for Muslims living in Europe and how they cope with challenges from rivals with different interpretations and fields of activism. It focuses on five Islamic communities active among Muslims originating from Turkey that represent the spectrum from moderate to revolutionary Islamic opinions: representatives of "official Islam" (Diyanet), political Islamists (Milli Görü?), a mystical Sufi order (Süleymanl?), Turkish civil Islam (Gülen) and a movement seeking an Islamic revolution in Turkey (Kaplan). The research included twelve months of intensive ethnographic fieldwork among Turkish Muslims in Germany and the Netherlands.