This article reviews and re-views societal constitutionalism, reflecting on its foundations, place, state, and horizons. It begins with a concise presentation of Niklas Luhmann’s social systems theory before charting the emergence and evolution of Gunther Teubner’s systems-theoretical approach to law. The article explains what attracted systems-theoretical scholars of law to constitutionalism and what concerns have motivated the elaboration of the systems-theoretical approach to societal constitutionalism. The article then introduces societal constitutionalism, distinguishing it from more familiar dominant approaches to constitutionalism and from other strategies for grappling with the constitutional implications of globalization. It nevertheless observes that many works that engage with societal constitutionalism do not deploy it as an alternative approach. Rather, these works draw on some of the insights of societal constitutionalism and on its external critiques of the dominant approaches to adapt the dominant approaches. The article concludes by welcoming this way of using societal constitutionalism and inviting societal constitutionalism to engage with other approaches in the same manner.