Unidad de excelencia María de Maeztu MdM-2015-0552In the development of national governance systems for Reducing Emissions fromDeforestation and forest Degradation (REDD+), countries struggle with ensuring that decision-making processes include a variety of actors (i.e., input legitimacy) and represent their diverse views in REDD+ policy documents (i.e., output legitimacy).We examine these two dimensions of legitimacy using Mexico's REDD+ readiness process during a four-year period (2011-2014) as a case study. To identify REDD+ actors and how they participate in decision-making we used a stakeholder analysis; to assess actors' views and the extent to which these views are included in the country's official REDD+ documents we conducted a discourse analysis. We found low level of input legitimacy in so far as that the federal government environment agencies concentrate most decision-making power and key land-use sectors and local people's representatives are absent in decision-making forums. We also observed that the REDD+ discourse held by government agencies and both multilateral and international conservation organisations is dominant in policy documents, while the other two identified discourses, predominantly supported by national and civil society organisations and the academia, are partly, or not at all, reflected in such documents. We argue that Mexico's REDD+ readiness process should become more inclusive, decentralised, and better coordinated to allow for the deliberation and institutionalisation of different actors' ideas in REDD+ design. Our analysis and recommendations are relevant to other countries in the global South embarking on REDD+ design and implementation