This study explores in depth the complex reaction of the Greek historian Polybius to the expansion of Roman power. Although he considered imperialism intrinsically noble, and both admired and supported Roman domination, Polybius also demonstrated a certain intellectual distance from Rome, evident in his application of abstract principles to the evaluation of Rome and other imperial powers, his acknowledgement of the aggressive drive underlying all imperial ventures, his willingness to criticize Rome, his concern for the interests of subject nations, the promotion of his own political views, and his willingness to contemplate the end of Roman power.