Modern scholarship on the historical-critical study of early Islam has yet to develop a systematic and nuanced approach to analysing isnāds in Imāmī ḥadīth collections, comparable to the methods pioneered by Joseph Schacht and G.H.A. Juynboll for Sunnī materials. This book addresses that gap by proposing a comprehensive methodological framework grounded in the written records produced within the Imāmī educational milieu of Medina during the second/eighth century. By integrating quantitative techniques with bio-bibliographical evidence, it offers new tools for dating Imāmī ḥadīths, reconstructing transmission patterns, and reassessing the early development of the Imāmī scholarly tradition.