This article argues that disarmament negotiations in Geneva played an important but hitherto little understood role in the evolution of French security policy after the First World War. While the majority of French policy-making elites remained unconvinced that collective security and arms reductions could ever form the basis of France's national security policy, they were forced to adapt to the changes in the international and domestic political contexts of the post-war era. Policy makers found it increasingly difficult to ignore the growing prominence of discourses of disarmament and mutual assistance both inside France and in international society. In order to adapt to changes in international norms, foreign policy evolved away from traditional strategies based on the balance of power and military alliances towards multilateral security pacts and an intensified focus on international law. This new approach, which was an amalgamation of traditional alliance politics and liberal internationalist principles, would remain at the centre of French diplomacy through to the mid 1930s.