This monograph offers a new analysis of fifth-century bc Athenian imperial power, a central topic in ancient Greek history. Challenging orthodox approaches, which have been mostly empirical, monolithic, and centred on Athens, the monograph argues that Athenian power was flexible and a matter of negotiation between the Athenians and their allies. The first three chapters focus on political, fiscal, and religious negotiations between the Athenians and their allies in Athenian contexts. The subsequent three chapters then offer studies of the empire in three different regions—the North Aegean, Rhodes, and the straits between the Aegean and the Black Sea—showing how the empire was formed of overlapping but differentiated regional manifestations. The monograph differs from previous studies in three key respects. Throughout, the monograph provides sophisticated economic analysis. It offers new perspectives on well-known Athenian epigraphic and literary sources, while also utilizing different categories of non-Athenian evidence, including varied forms of material culture. Finally, it makes use of critical historical comparison: with other imperial powers, with later Athenian power, and most of all with the operation of fifth-century Athenian power in different regions.