What drives policymakers and citizens to perceive another state’s claim as maximalist, and how do these perceptions influence policy responses? This paper presents three studies that explore the drivers and consequences of perceiving an adversary’s claims as excessive. Each study employs a survey experiment, using either a hypothetical or real boundary dispute with varying claim sizes. The first study examines the role of claim size and how it is shaped by the regime type of the claimant state and information about international law. The second and third studies investigate how information about international law and the legal strength of claims shapes perceptions and influences preferred foreign policy responses. Each study also considers how variations in hawkishness and trust in international institutions affect these perceptions, while exploring the mechanisms through which the perception of maximalism is sustained. Together, these studies provide new insights into the factors that shape perceptions of maximalism and their role in international dispute processes.