Abstract This chapter explains the interrelations between constitutional and international law with special emphasis on the sources or clauses of international projection in the Constitutions of the Americas and the Caribbean. Through the description and analysis of the normative taxonomies of each of the 36 Constitutions in force in the region, we offer a big picture of the internationalization of constitutional law and at the same time of the elements that make up the constitutionalization of international law in the region. The connections are demonstrated through practical examples of the impact on domestic legal systems in the areas of human rights, regional integration, and investment law. The main contribution of this study lies in subsuming in a few pages the identification of the intersections of international and constitutional law in the Americas with a view to the relations between the local, national, regional, and international.