The Musta‘lī (Arabic: مستعلي) are a sect of Isma'ilism named for their acceptance of al-Musta'li as the legitimate nineteenth Fatimid caliph and legitimate successor to his father, al-Mustansir Billah. In contrast, the Nizari—the other living branch of Ismailism, presently led by the Aga Khan IV—believe the nineteenth caliph was al-Musta'li's elder brother, Nizar. Isma'ilism is a branch of Shia Islam.
The Musta'li originated in Fatimid-ruled Egypt, later moved its religious center to Yemen, and gained a foothold in 11th-century North India through missionaries.
Historically, there was a distinction between the Taiyabi and the Hafizi Musta'lis, the former recognizing at-Tayyib Abu'l-Qasim as the legitimate heir of the Imamate after al-Amir bi-Ahkami'l-Lah and the latter following al-Hafiz, who was enthroned as caliph. The Hafizi view lost all support following the downfall of the Caliphate: current-day Musta'lis are all Taiyabi.
Most Musta'li are Bohras, and the largest Bohra group is the Dawoodi Bohra, who primarily found in India. The name Bohra is a reinterpretation of the Gujarati word vahaurau "to trade". The Bohra comprise two principal groups: a chiefly merchant class Shi'i majority and a Sunni Bohra minority who are mainly peasant farmers.
Mohammed Burhanuddin was the 52nd Da'i al-Mutlaq of the Dawoodi Bohra community. After his death, there was a dispute regarding succession with both Mufaddal Saifuddin and Khuzaima Qutbuddin claiming to be the 53rd Da'i al-Mutlaq. This dispute is unresolved.