An extensive literature shows that information-creating mechanisms enhance the transparency of and can support participation and compliance in international agreements. This paper draws from game theory, international relations, and legal scholarship to make the case for how transparency through policy surveillance can facilitate more effective international climate change policy architecture. I draw lessons from policy surveillance in multilateral economic, environmental, and national security contexts to inform a critical evaluation of the historic practice of monitoring and reporting under the global climate regime. This assessment focuses on how surveillance produces evidence to inform policy design, enables comparisons of mitigation effort, and illustrates the adequacy of the global effort in climate agreements. I also describe how the institution of policy surveillance can facilitate a variety of climate policy architectures. This evaluation of policy surveillance suggests that transparency is necessary for global climate policy architecture.