Fritz Meier (1912-1998) is one of the most outstanding Orientalists of this century. His publications combine masterful philological method and precision, profound and penetrating textual interpretation, and a wide-ranging familiarity with primary sources which may truly be characterized as phenomenal. Among the numerous fields in which he has undertaken original research, Persian poetry and Islamic mysticism (Sufism) in the widest sense stand out in particular. His work on Sufism covers the whole of the Islamic world and Islamic history from its beginnings up to the 20th century. The present provides for the first time a translation of 15 of Fritz Meier's seminal articles. The selected articles deal with the history of Sufism; Sufi morals and practices such as dhikr and samā‘; the historical development of the master-disciple relationship; Ibn Taymiyya's attitude toward Sufism; pious devotional practices such as making use of the tasliya; essential sources for the history of Sufism in the Maghreb and the Almoravids. Extensive indices facilitate the use of this epoch-making work.