I have previously dealt with the authorship and transmission of Ibn Sa?d’s ?abaq?t from the 3rd and up to the 9th Islamic centuries. I showed that the life of this book had four pivotal moments: its conception in the 3rd, its re-compilation in the 4th, its popularization in the 5th, and its migration to Damascus in the 6th. This paper is an attempt at explaining these four pivotal moments; which constitutes a social history of the book as conceived of by Robert Darnton. I attempt to answer the following: Why did Ibn Sa?d writehis ?abaq?t? Why did all recensions disappear from the market and only a 4th century re-compilation survive? Why did al-Kha??b al-Baghd?d? popularize the book in the 5th? And why did Ibn ?As?kir (6th) depend so heavily on it for the writing of his T?r?kh Dimashq? Based on organizational difference between Ibn Sa?d’s abridgement of the ?abaq?t (still in manuscript) and the full version of the book, I attempt to answer the conception question. Ibn Sa?d lived during al-Ma’m?n’s Mi?na which was mainly directed at the Baghd?d? ?ad?th transmitters. It is no surprise that the ?abaq?t is a biographical dictionary of ?ad?th transmitters. I argue the deep involvement of Ibn Sa?d in the Mi?na, to which the writing of the ?abaq?t was a response. The increasing Sunn? orientation of the ?Abbasid Caliphs following the end of the Mi?na during the reign of al-Mutawakkil (c. 237 AH) will serve as the point of departure for my answer to the fourth century re-compilation of the ?abaq?t. Furthermore, if M. Q?sim Zam?n (Religion and Politics under the Early Abbasids) considered the mu?addith?n of the third century as proto-Sunn?s, it is clear that by the fourth century, especially during the Buyid period, they were at the heart of Sunnism. It is during this period that we see the recompilation of the ?abaq?t and its popularization, as a confirmation, I argue, of the mu?addith?n’s central role in defining Sunnism and countering the influence of Sh??ism. Finally, the migration of the ?abaq?t to Damascus on the hands of Ibn ?As?kir is a part, I argue, of his implementation of N?r al-D?n Zeng?’s policy of Jih?d against the Crusaders; the central piece of which was the establishment of ?ad?th houses and the sanctification of Syria by linking it to Mu?ammad’s companions.