In this original study, Elizabeth R. Alexandrin examines the complex relationships that can be inscribed between medieval Ismā'īlī thought as an intellectual tradition with a devotional practice of reliance on the imām, and as a politico-esoteric system that redefined governance during the Fāṭimid caliphate in the eleventh century. Alexandrin's work is a departure from recent Western scholarship that focuses on similarities among early Islamic traditions. She argues instead that, under the guidance of the Fāṭimid Ismā'īlī chief missionary al-Mu'ayyad fī al-Dīn al-Shīrāzī (d. 1078 CE), the concept of walāyah (divine guidance) became closely associated with religio-political authority, on the one hand, and the perfection of the individual human being, on the other. By signaling and affirming how the Fāṭimid caliph-imāms were the heirs of walāyah and by proposing new definitions of the "seal of God's friends" (khātim al-awliyā' Allāh), al- Mu'ayyad broadened the contexts of making esoteric knowledge public and shifted the apocalyptic frameworks of Islamic messianism.