The article seeks to add to the growing contribution of discursive approaches to the study of political institutions by analysing the possibilities for cross-fertilisation between discursive institutionalism and post-structuralist discourse theory. Analysing Vivien Schmidt's version of discursive institutionalism, it argues that Schmidt's concept of discourse results in a model of explanation of institutional change that overlooks questions about the relations between power, politics and discourse. It further argues that while post-structural discourse theory has made important contributions to the understanding of the discursive nature of social practices, it has so far failed fully to take on board the institutional dimension of politics. It concludes that an integration of Schmidt's insights on discursive institutionalism with post-structuralist discourse theory allows a more rounded analysis of the political dimension of institutions and of the institutional dimension of politics, as well as a better understanding of institutional change. To illustrate our arguments we draw on our own research to analyse the relations between discourse and institutions in the 2002 presidential electoral campaign in Brazil and in Argentina's poverty reduction policies in the 1990s.