Reputation is key to understanding a wide range of outcomes in international politics, from military disputes and alliance formation to states’ compliance with international legal and financial obligations. However, the micro-foundations of reputation – how it forms and, crucially, whom it adheres to – remain poorly understood. Recent experimental research finds that, while reputations adhere to countries and to leaders, country-specific reputation outweighs leader-specific reputation even when leaders have complete control over foreign policy. This presents a puzzle: why do leader-specific actions generate country-specific reputations? Drawing on the psychology of attribution and group perception, I offer a theory of why observers form country-specific reputations. Focusing on reputations for resolve, I employ an online survey experiment to test the theory. The findings help understand how countries acquire the properties of agents in international politics and anticipate the consequences that a country’s foreign-policy choices have on its prospects for cooperation with friends, or deterrence of foes, in the future.