This paper examines the way that the concept of citizenship might be used by social movements in developing countries to advance their claims for basic rights from the state. It is based on findings from a year’s fieldwork with a social movement that organises around the provision of low-income housing in São Paulo, Brazil. In order to situate the discourse of the movement, the paper begins by discussing the varied interpretations of citizenship and how citizenship can be jeopardised by poverty. The paper then shows how the framing of basic rights as ‘citizenship rights’ has become a powerful weapon in the movement’s campaigning that is focused on the state. There are a number of implications of using citizenship rights to frame a social movement’s claims. Perhaps most importantly, it brings the law into play, as social movements and their supporters prosecute the state for not ensuring that the rights of its people, as outlined in the Constitution, are upheld. In a type of paradox, the movements also use radical and formally illegal types of protest in order to highlight what they perceive as the state’s own illegality. The paper ends by presenting the significance of these findings for development work and international NGOs.