Ismailis (ismäēl'ēz) [key], Muslim Shiite sect that holds Ismail, the son of Jafar as-Sadiq, as its imam. On the death of the sixth imam of the Shiites, Jafar as-Sadiq (d. 765), the majority of Shiites accepted Musa al-Kazim, the younger son of Jafar, as seventh imam. Those who remained faithful to Ismail, the eldest son, soon evolved the belief that Ismail was endowed with an infallible gift for interpreting the inner meaning of the revelation.
Ismailism developed an understanding of Islam and promoted it through an active missionary system. Although the early history remains obscure, Ismailism incorporated elements of Gnosticism, Neoplatonism, and Hindu thought to explain its concept of the imam. Over time it came to stress the importance of the esoteric aspects of the faith over the exoteric. The first success of the Ismaili movement was the establishment of the Qarmat state (see Karmathians) in E Arabia. Ismaili missionaries and its political organization also mobilized a network of N African tribes to support the Fatimid claim to the caliphate in Egypt and several regions of the Mediterranean. An offshoot, the Assassins, established a state in NE Iran, which survived until the 13th cent. In 1094 the Ismailis split into Nizaris and Mustalis. Today, though a minority community that is not politically active, the Ismailis are spread in small pockets in parts of the Middle East, central and S Asia, and increasingly North America and Europe. The family of the Aga Khan, the Nizari imam, traces its descent from Ismail.
See S. M. Stern, Studies in Early Ismailism (1983); F. Daftary, The Ismailis (1990).