One of the most enduring sources of conflict among Muslims is the question of power and authority after the Prophet Muhammad. This anthology of classical Arabic texts, presented in a new English translation, offers a comprehensive overview of the early history of the caliphate and key questions that medieval Muslim scholars discussed in their works on the subject. Composed between the eleventh and thirteenth centuries, these texts succinctly present competing views on the prerequisites of legitimate leadership and authority in the Islamic tradition. This volume offers an engaging introduction to the diverse writings of influential scholars representing six classical Islamic schools of theology: Sunnism, Zaydism, Twelver Shiʿism, Muʿtazilism, Ibadism, and Ismaʿilism.