This chapter will trace the development of the Mustaʿliyya (or Mustaʿlawiyya) branch of Ismāʿīlism, from its origins in 487/1094 up to the present. Until the year 524/1130, the Mustaʿlian Ismāʿīlīs of Egypt, Syria, Yaman and elsewhere constituted a unified group, as distinct from the Nizāriyya. By then, the Mustaʿlians had recognized two more imams in the persons of al-Mustanṣir's son and grandson, al-Mustaʿlī and al-Āmir. However, in the confusing aftermath of al-Āmir's death in 524/1130 and the claims of al-Ḥāfiẓ, al-Āmir's cousin and successor in the Fāṭimid caliphate, to the imamate, a new split occurred in the Mustaʿlian community, subdividing it into the Ḥāfiẓiyya and the Ṭayyibiyya. Both of these factions of Mustaʿlian Ismāʿīlism will be discussed in the present chapter.

The Ḥāfiẓiyya, also known as the Majīdiyya, accepted al-Ḥāfiẓ and the later Fāṭimid caliphs as their imams after al-Āmir. The Ḥāfiẓī cause, officially endorsed by the Fāṭimid daʿwa in Cairo, found the bulk of its supporters in Egypt and Syria. It received support also in Yaman, where the local dynasties of the Zurayʿids of ʿAdan and some of the Hamdānids of Ṣanʿāʾ supported the Ḥāfiẓī daʿwa. The Ḥāfiẓiyya, however, did not survive for long after the fall of the Fāṭimid dynasty in 567/1171.

The Ṭayyibiyya, initially known as the Āmiriyya, recognized al-Āmir's infant son, al-Ṭayyib, as their imam after al-Āmir, rejecting the claims of al-Ḥāfiẓ and his successors on the Fāṭimid throne to the imamate.