This Article examines the adoption of rights in national constitutions in the post-World War II period in light of claims of global convergence. Using a comprehensive database on the contents of the world's constitutions, we observe a qualified convergence on the content of rights. Nearly every single right has increased in prevalence since its introduction, but very few are close to universal. We show that international rights documents, starting with the Universal Declaration of Human Rights, have shaped the rights menu of national constitutions in powerful ways. These covenants appear to coordinate the behavior of domestic drafters, whether or not the drafters' countries are legally committed to the agreements (though commitment enhances the effect). Our particular focus is on the all-important International Covenant on Civil and Political Rights, whose ratification inclines countries towards rights they, apparently, would not otherwise adopt. This finding confirms the complementary relationship between treaty ratification and domestic constitutional norms, and suggests that one important channel of treaty efficacy may be through domestic constitutions.