The "inquisition" (Mihnah) unleashed by the seventh Abbasid caliph, 'Abdallah al-Ma'mun (r. 813-833), has long attracted the attention of modern scholars of the intellectual, political, and religious history of the early Abbasid era. Historians have seen it as the key to a wide array of puzzles and problems in early Islamic history. In this incisive study, John Nawas subjects the various proposed explanations of these events to a sober and searching analysis and, in the process, presents a new interpretation of al-Ma'mun's political and religious policies, contextualized against the background of early Abbasid intellectual and social history. Appended to the volume is a reprint edition of Walter M. Patton's Ahmed ibn Hanbal and the Mihna (Leiden 1897), which still has much that is useful for modern scholarship, including one enormous additional benefit; it contains most of the relevant passages in Arabic from the primary sources