"This article proposes a conceptual framework of social innovation based on theories of institutional change and applied to Latin-American solidarity economy. Social innovation is conceived as a change in the codification of social relations that validates new principles of coordination produced by reflexive actors. This framework is used to interpret two transformations driven by solidarity economy initiatives in the case of the city of El Alto, in Bolivia: the transformation of the production relationships and of gender relationships. The reach of two types of innovation is evaluated: the affirmation of an original principle of reciprocity in the mode of production; and of a principle of equality in access to the public and the productive spheres. JEL Codes: B5, D02, O1, P4, Z13"