This chapter examines the impact of European integration on the Treaty of Lausanne's homogeneous nation-state model, with particular attention to Greek-Turkish relations. It starts by tracing the Treaty’s historical influence on British and German policies until the late 1940s. Resorting to archival material from European institutions, the chapter moves on to argue that the European Union’s freedom of movement has since then contested the Treaty’s legacy and has had the potential to reshape Greek-Turkish relationships. The analysis suggests finally that a possible Turkish rapprochement with the EU could pave the way for new forms of cooperation and conflict resolution in the region.