The Institut de Droit International (IDI) and the International Law Association (ILA) have bequeathed complex and contradictory legacies to the Americas. This essay explores both the resonances and the dissonances that the formation of the IDI, and to a lesser extent, the ILA, had in the institutionalization of the modern discipline of international law in the Americas. On the one hand, the IDI's establishment as an elite Eurocentric organization with a missionary imperial approach to the promotion and reform of international law, generated resonances across the Americas, inspiring the creation of the American Institute of International Law (AIIL). On the other hand, the AIIL emerged as a reaction to the IDI, insofar as the former promoted juridical values based on the idea of American international law and a distinctive sense of U.S. and continental legal exceptionalism. The essay argues that the institutionalization of international law in the Americas was both inspired by the Eurocentric imperial and elitist legal approach promoted by the IDI, and the desire to forge a distinctive Western Hemispheric counterpart: a continental American international law.