This text presents the "Chapter on Satan" (Bab al-shaytan) from an Ismaili work called the "Kitab al-Shajara" by the 4th/10th-century Khurasani da'i, Abu Tammam. The satans of Tammam's "Chapter" are the founders and instigators of the 72 heretical sects of Islam. Each sect has been accorded a relatively lengthy description as perceived from a generally Shi'i and Mu'tazili point of view. The volume contains both a critical edition of the "Bab al-shaytan" and a complete English translation of it.