The Parthian empire was one of the most enduring and transformative polities of the ancient world, but for all its importance it remains poorly understood. Under the leadership of the Arsacid dynasty, the Parthians rose from humble beginnings in northeastern Iran to rule a territory that stretched from Asia Minor to the central Asian steppe. Their empire encompassed a vast array of peoples, cultures, and religions, and its long tenure on the Iranian plateau gave it a central role in shaping the history of the Near East and the region's interaction with the wider ancient world. Despite its importance to world history, however, the study of the Parthian empire is ill-served by existing scholarly resources. This handbook provides an accessible guide to the sources for Arsacid history as well as thematic essays that synthesize recent advances in the specialist literature. By balancing a comprehensive treatment of the empire with high-resolution studies of its different cultures, regions, and bodies of evidence, the handbook will serve as an indispensable reference for the study of Parthia by bringing the Arsacid past to the attention of an audience with interests in ancient history, archaeology, comparative literature, anthropology, and religious studies.