International relations scholarship often describes America’s foreign policy tradition as having isolationist tendencies or an isolationist dimension, a characterization derived most directly from American security policy in the 1920s and 1930s. This article offers a critique of this characterization. American diplomacy in the 1920s was subtle but ambitious and effective. American policy in the years leading up to the bombing of Pearl Harbor was in fact quite responsive to events on the European continent. In short, American isolationism is a myth.