Abstract: In recent years, regions are taking a decisive role in world trade liberalization. Their greater activity and presence in the international scene indicate the existence of greater opportunities to study them from a comparative perspective. However, its study has been strongly limited from an internal viewpoint, aimed at describing and analyzing the internal characteristics of the region that favor its cohesion and its external performance. This is due to, among several reasons pointed to by the academic literature of regionalism and interregionalism, the difficulty of conceptually defining the region and its changing structure. This study aims to review the main contributions of the International Relations discipline in the field of regional cohesion and explore the possibilities of analyzing the regions from a comparative perspective. It concludes that there has been a special emphasis on analyzing cohesion from the perspective of regional institutions and state preferences, particularly in studies on the European Union. However, other factors of cohesion identified by academic literature, such as the distribution of power or regional coherence, have been developed to a lesser extent.