Institutional change and diversity have been two major topics of debate in contemporary social sciences. At the core of this debate are actors' skills to manage the institutional frame that defines limits and possibilities for their strategies. This article analyses how social movements produce institutional change and diversity in the organic food market. It contrasts the experiences of Participatory Guarantee Systems created by Nature & Progrès (France) and Ecovida Agroecology Network (Brazil) to reframe the institutional order of the organic market. Results demonstrate that, while the conventional third-party certification remains the dominant institutional frame, there is space for competing schemes. However, the relevance of the alternatives depends both on the characteristics of the institutional order historically shaped in each context, and on the skills social movements possess to face the interests of the dominant actors. In this way, the article demonstrates that, in comparison to Nature & Progrès, Ecovida has been a more skillful movement because of its closer connection with other social movements and state actors, compelling Brazil to produce an institutional frame more open to diversity than that found in France.