The thirteenth volume based on the Giorgio Levi Della Vida conference series at UCLA assesses the role played by the Iranian peoples in the development and consolidation of Islamic civilization. In his key chapter, Ehsan Yarshater casts fresh light on that role, challenging the view that, after reaching a climax in Baghdad in the ninth century, Islamic culture entered a period of stagnation and decline. In fact, he maintains, a new and remarkably creative phase began in Khurasan and Transoxania, symbolized by the adoption of Persian as the medium of literary expression. Persian literary and intellectual paradigms and a mystical world-view spread from Anatolia to India. By the mid-sixteenth century, they were being supported and cultivated in the three empires that encompassed the greater part of the Islamic world: the Ottoman, the Safavid, and the Mughal. Professor Yarshater also challenges some traditional assumptions and recent claims about the "Islamization of Persia" or "Persianization of Islam." In the chapters which follow, six distinguished scholars consider the historical, cultural, and religious aspects of the Persian presence in Islamic civilization.