Scholars of international law and international relations largely agree that global governance today, and global environmental governance in particular, is marked by institutional complexity. Environmental policy fields are, to varying degrees, governed by a plurality of institutions with different levels of legalization, membership, and jurisdictional scope, and with different degrees of coherence among them. The international governance architecture on Reducing Emissions from Deforestation and Forest Degradation (REDD+) is a case in point. Located at the intersection of the governance systems on climate change, biodiversity, forestry, and development, REDD+ governance provides a stage where a large variety of intergovernmental and transnational institutions come together, collaborate, or compete on questions of standard-setting, financing, implementation, and evaluation. This complexity poses challenges to the effectiveness of REDD+ governance in general, but also to specific actor groups and organizations that lack the resources to understand and navigate such a fragmented governance landscape. Against this backdrop, we introduce an analytical framework to read and structure a complex governance architecture. The framework breaks new ground by adopting argumentative discourse analysis and the concept of storylines to the study of institutional complexity. We argue that beyond the messy surface of institutional complexity there may be a surprising degree of convergence, in the sense of discursive hierarchies that run across institutions, practices, and scales. We illustrate such a cross-cutting hierarchy for the complex REDD+ governance system, focusing on the sensitive issue of forest carbon monitoring. In our analysis of respective guidance documents and country reports, we find, underneath the institutional complexity across governance scales, a considerable dominance of techno-managerial perspectives and a preference for carbon commodification. This discursive hegemony and convergence resonates with the dominance of certain REDD+ funding institutions and the prioritization of the monitoring practice of remote sensing.