Polybius’ Histories, written in the mid—second century BC, offers an authoritative account of Rome’s rise to uncontested imperial supremacy. The work has been highly influential among political thinkers because of its theory of the “mixed constitution.” This essay proposes to return Polybius’ mixed constitution to its proper location within the narrative of the Histories. This interpretative approach enables us to appreciate Polybius’ frequently neglected emphasis on the connections between republican politics and Roman imperial power. These connections shed light on recent (...) developments in republican political theory. They also lead to an investigation of the didactic purposes of the author, who intended to educate the Roman aristocracy in the virtues necessary for exercising hegemonic power successfully in the ancient Mediterranean world. (shrink)