The role of compromise in EU politics has been widely recognized by scholars and practitioners alike. At the same time, the systematic conceptual, analytical and normative study of compromise has remained an exception. This is surprising, given that the study of compromise can be linked to three broader questions at the heart of integration: (1) How does the EU accommodate diversity? (2) What makes supranational rule normatively justifiable? (3) Who or what defines the limits of cooperation? Against this backdrop, this article sheds light on the concept of compromise, on the role of compromise in legitimizing supranational governance and on the limits to compromise in the European polity. I argue that the EU – a divided, multilevel and functionally restricted polity – is highly dependent on the legitimizing force of ‘inclusive compromise’, which is characterized by the recognition of difference. This is true for horizontal or micro-level relations between political actors (where compromise works through concessions as well as justification, perspective-taking and empathic concern in a process of ‘procedural accommodation’), and for vertical or macro-level relations between systems of governance (where compromise works through ‘constitutional compatibility’). Given the legitimizing force of inclusive compromise, I subsequently identify the limits to such agreements and, thus, to supranational cooperation; I argue that these limits are issue specific and depend on where the costs of cooperation are borne. The article concludes by outlining routes for follow-up empirical research.