This issue is dedicated to the phenomenon of Muslim mysticism and heterodoxy. Time frames of the presented researches cover different periods: from the Abbasid Caliphate to modern times. Thematically, the materials mainly cover the entire Muslim Oecumene, i.e. Mesopotamia, Maghreb, Ottoman Balkans, Khorasan, and Pamir Highlands. They cover both theoretical and practical aspects of Muslim heterodoxy: history, doctrine, and folklore. They are based on both written sources and field research materials.