This dissertation examines the performance of REDD+ MRV in terms of its implementation and institutionalization in developing countries, and the political processes by which such institutionalization occurs. Specifically, it examines (1) the institutional effectiveness of REDD+ MRV; (2) how the concept of REDD+ MRV and associated ideas have materialized in new institutional arrangements for forest monitoring in developing countries; and (3) how discursive processes of policymaking and the argumentation and contestation inherent in such processes enable or constrain institutionalization. With this, the dissertation contributes to the literature on REDD+ MRV by examining forest monitoring from a social science perspective. While current research on REDD+ MRV remains highly technical, since it is assumed that forest monitoring is a neutral, apolitical activity, this study argues that monitoring deforestation is also political, and contributes by highlighting the political contestation involved in implementing REDD+ MRV at the national level. The dissertation also contributes to scientific debates on the performance of international environment agreements at the national level, and how contestation and negotiation among domestic stakeholders enable or constrain their institutionalization at the national level.