The goal of reducing emissions from deforestation and forest degradation, and the roles of conservation, sustainable management of forests and enhancement of forest carbon stocks in developing countries (REDD +) under UNFCCC has triggered a new discussion on forest resource assessments in these countries. The international process on measurement, reporting and verification of REDD + outcomes (REDD + MRV) expands the scope of forest inventories to include quantification of forest carbon stocks and their changes for results-based REDD + payments. UNFCCC decisions also specify methods to be used, and actors to be involved. Although forest management in developing countries has clearly been influenced by international processes in the past, exactly how and to what extent REDD + MRV has affected institutional arrangements for forest assessments in developing countries remains unknown. Using as a theoretical framework Discursive-Institutionalism, a concept derived from political science, this paper examines (1) the historical evolution of institutional arrangements for forest inventories in Peru; and (2) how and to what extent their development has been shaped by international processes on forests, and, more recently, specifically by REDD + MRV. The findings show that the international REDD + MRV discussion has expanded the objectives of forest assessments in Peru, inspired the mobilization of new actors and resources, and spawned the development of new protocols for forest assessments. However, the 'depth' of these changes is not yet extensive, since the new rules for forest inventories have not yet been formally adopted, and the institutes envisaged to implement forest inventories, including measurement of carbon stocks and their changes, have not been established.