A crucial development in current Latin American politics is the growing involvement of indigenous movements in democracies grappling with the challenges of regime consolidation. This article examines how Ecuadorʼs indigenous movement consecrated new rights and national constitutive principles in the 1997–8 constitutional assembly. It argues that the indigenous movement defined the legitimacy and purpose of the assembly through an ideological struggle with other political actors, in turn shaping the context and content of constitutional reforms in Ecuador. The article concludes that softening the boundary between ‘cultural politics’ and ‘institutional politics’ is necessary in order to understand the impact of social movements in Latin America.