This article examines the impact of participatory institutional arrangements between different social and civil organizations in Brazil. Taking the field of social assistance as a case study, the article argues that various institutionalized mechanisms for citizen participation, such as conferences and management councils, promote the development of a “vertical” sectoral network, through which public policies can be controlled from the federal to the local level, and a “horizontal” territorial network, in which various sectoral issues are activated within the same territory. This dual articulation promotes greater associative density: the territorial networks have better knowledge of the specific policies implemented in their cities; and the sectoral networks, besides participating in all stages of policy implementation, can understand their impact at the national and local level.