ENThis article is a modified and expanded version of the British Academy Raleigh Lecture, delivered at Queen’s University Belfast. It argues that historians, as opposed to political scientists, sociologists, and philosophers, have neglected the history of compromise and compromises, despite compromise being a significant social and political practice. It considers how historians might approach the problem of compromise, and what a historical perspective might add to study of compromise. It concludes with a comparative consideration of three political unions, between Poland and Lithuania, between England and Scotland, and between England/Britain and Ireland from the point of view of a historian of compromise. Keywords: History of compromise, history of trust, history of political union, Polish-Lithuanian Union, British Union, Union of Britain and Ireland, sovereignty and post-sovereignty. [From the publication]