--- - |2 Abstract Constructivism in most of its variants emphasises the creation of circumstances and the social construction of reality. In international relations theory (IR), it also emphasises the establishment of international regimes. The Suez Canal and its governing regime, established at a high point of European nationalism and imperialism in the nineteenth century, are explored as a test case. I argue that, while the early history of the Canal is illuminated by a constructivist approach, maintenance of the regime to govern it involved military intervention and debt restructuring. Military force, balance of power considerations and economic interests all have to be invoked to explain the later history of the Canal, that is, factors usually stressed by the realist school. A combination of realist and constructivist approaches is recommended. The paper is also critical of certain constructivist concepts of national identity. - 'Nations and Nationalism, EarlyView. '