This chapter examines the distinctive beliefs and practices of the Twelver Shi‘is. More specifically, it discusses the origins and subsequent development of Shi‘i beliefs and jurisprudence. Drawing specifically on Shi‘i sources, it will also compare and contrast Shi‘i practices with its Sunni counterpart. The chapter also argues that the belief in the suffering of the family of the Prophet (ahl al-bayt) created a distinctly Shi‘i pathos which emphasized the return of the eschatological Messiah to remove the injustices they endured. Moreover, the martyrdom of Imam Husayn in Kerbala, Iraq engendered specific rituals and social practices that clearly differentiated Shi‘ism from Sunni Islam.