The objective of this paper is to analyze the experience of the Solidary Economy in Brazil, focusing on the organization and political meaning of a Municipal Forum of Solidary Economy in a city of the metropolitan area of Porto Alegre, Rio Grande do Sul State. Based on the theoretical/empirical framework that underpins our research and academic extension activities, we intend to understand the implementation of this model of political self-organization and how it can redefine and implement a new political practice. With this purpose, we divided our analysis into three different moments: a brief overview of the Solidary Economy in Brazil; a description of the organization and design of the Municipal Forum of Solidary Economy as well as how this organizational model becomes part of everyday practice; and, finally, an analysis of the role played by trade fairs as learning environments, aiming to build a solidary rationality capable of redefining the political environment as a space for the practice of solidarity.Keywords: Solidary Popular Economy, self-organization, solidarity.