This book evaluates a hundred years of scholarship on how empire transformed the Roman world, and advances a new theory of how the empire worked and was experienced. It engages extensively with Rome's Republican empire as well as the 'Empire of the Caesars', examines a broad range of ancient evidence (material, documentary, and literary) that illuminates multiple perspectives, and emphasizes the much longer history of imperial rule within which the Roman Empire emerged. Steering a course between overemphasis on resistance and overemphasis on consensus, it highlights the political, social, religious and cultural consequences of an imperial system within which functions of state were substantially delegated to, or more often simply assumed by, local agencies and institutions. The book is accessible and of value to a wide range of undergraduate and graduate students as well as of interest to all scholars concerned with the rise and fall of the Roman Empire.