Within constitutional theory, in comparison to other fields of scholarship, the significance of transnational social movements has been relatively unexamined in the literature. Societal constitutionalism, grounded in the sociological method and open to reexamining received understandings of constitutionalism, would appear conducive to undertaking this enterprise. However, the general absence of social movements from the societal constitutionalism literature is not coincidental, and reflects a shared commitment with more conventional approaches to an institutional conception of constitutionalism, and a belief in the latter’s necessary benevolence and Western origin. These assumptions reflect the limited focus of contemporary analyses of globalization and constitutionalism upon “globalization from above.” As key protagonists within “globalization from below,” social movements represent a form of “constitutionalism from below.” Incorporating social movements within constitutional discourse deepens the sociological turn favored by societal constitutionalism by revealing the always-existing noninstitutional dimension of constitutionalism. Moreover, doing so locates in social movements the potential for a transformative constitutional agency which has often proven elusive.