My dissertation examines the Deoband madrasa {Islamic school) of North India, whose curriculum has been copied and adapted by Islamic schools all over the world. Despite the media attention that Deoband has received in recent years, due to the revelation that some Taliban studied in Deobandi madrasas in Pakistan, this extremely important institution has been the subject of only one academic monograph in English and a small number of articles, most of which touch on Deoband only tangentially. Based on my previous research in the study of South Asian Sufism, or Islamic mysticism, my project takes as its point of departure the contentious relation between Deobandis and Sufis from the mid-19th century to the present. My research thus addresses larger problems in the field of religious studies regarding the nature of intra-religious polemic and dialogue. My dissertation research has two goals: first, through archival research at the original Deoband madrasa in India, it examines an ambivalence in how the founders of Deoband at once derived so much of their personal understanding of Islam from Sufism, and yet embarked on a systematic and trenchant critique of Sufi practices; second, through fieldwork and participant-observation in South Africa, it follows these critiques to discern how they travel in the South Asian diaspora and how contemporary Deobandis adapt, modify and/or contest these critiques. My archival work in India examines the first part of this ambivalence - Deoband's Sufi roots - and my fieldwork in South Africa examines the second part - the trajectory of their anti-Sufi stance in the contemporary world.