The idea that citizens possess duties, in addition to rights, appears to be growing in popularity. As we are witnessing a growing backlash against the liberal constitutional model that heavily emphasizes individual rights, religious and conservative voices are calling for an emphasis on individual duties and responsibilities. This Article shows that duties for individuals have always been common in national constitutions. No less than 64 percent of all constitutions include at least one duty; such as the duty to “respect the constitution,” “defend the country,” and “pay taxes.” Drawing on original data that captures the historical trajectory of constitutional duties in national constitutions, we document the first instances of adoption and their global spread. We code what type of duties are most common and their evolution. Although legal scholarship has had little to say about constitutional duties, they have long been part of a liberal constitutionalism enforced by many courts.