The article proposes an innovative theoretical framework outlining preconditions for Regional International Courts (RICs) to act as engines of supranationality in different institutional and socio-political contexts. In so doing, the article nuances the theoretical approaches to supranationality and supranational adjudication. The article focuses on the Central American Court of Justice (CACJ) and the Caribbean Court of Justice (CCJ). Both courts have been branded institutional copies of the Court of Justice of the European Union (CJEU); they have even borrowed key jurisprudential principles from the Luxembourg Court with the goal of expanding the reach of Central American and Caribbean Community Laws. Yet, both the CACJ and the CCJ have thus far failed to foster supranationality in their respective systems. This is because the conditions allowing RICs to become engines of integration lie, for the most part, beyond the direct control of the judges, most notably, with other institutional, political, and societal actors, such as national judges, regional organs, legal and political elites, as well as academics. The article thus suggests that RICs can become engines of supranationality only to the extent to which they are supported by a set of institutional, political, and societal pre-conditions allowing for the concrete enforcement of the rulings of the RIC at the regional and national levels.