The Sufi tradition as the 'other face' and 'soft core' of Islam represents a particular creative and liberal facet characterized by tolerance, humanism and the accommodation of differences. That is why inspirational Sufi religiosity is inclusivist in nature. This book, which understands Sufi Islam as being embedded in wider social and cultural contexts, surveys the whole of the Muslim world from Sub-Saharan Africa across the Middle East to Eastern Turkestan and South Asia, with particular emphasis on Pakistan and India as its demographic centre. What distinguishes this study most clearly from the considerable number of introductions to Sufism currently available is that it offers an account of Sufi Islam from the perspective of the ethnographer as much as that of the historian of religion. Focusing on its concrete, practiced and lived forms, it shows how popular Sufism developed into the almost ubiquitous mass movement, present at all levels of Muslim society as a dynamic force until modern times. This book is a revised translation of the original German edition.