Neglected since his death after having been all at once criticized and hailed during his lifetime, Raymond Aron’s approach challenges any easy classification within the discipline. An interesting attempt has been proposed by Michael Doyle, who considers Aron to be a constitutionalist realist. While basically agreeing with this proposal, our contribution purports to show that Aron actually was a neo-classical realist before the term was invented. After recalling Aron’s common points with Morgenthau’s classical realism and Waltz’s neo-realism, the article analyses the numerous epistemological and ontological affinities linking the French IR scholar to the contemporary North-American neoclassical realists who ignore that they ignore Aron.