This article investigates the Franco-British rapprochement in security and defence cooperation under Nicolas Sarkozy, Gordon Brown and David Cameron from 2008 to 2012. While in the past British Atlanticism and the French Europeanist tradition had stood in the way of close bilateral cooperation, the conclusion of several treaties of defence cooperation in this period delivered closer ties. By adopting an interpretivist perspective on events, this article argues that the rapprochement can be explained with reference principally to changes in the French tradition, which took it closer to the British Atlanticist tradition. Drawing on parliamentary and executive statements, the article traces the influence of, and changes in, the balance between Europeanism and Atlanticism in the defence policy traditions in the two countries. The article argues that the dilemmas that compelled a revision of the traditions particularly in France arose from a series of new beliefs at elite level about sovereignty over defence policy, national role conceptions and the recognition of dire budgetary constraints. In this context, Franco-British rapprochement served both countries' national interests.