The Paris Agreement represents a decisive turning point in the global response to climate change. Through an innovative hybrid structure blending “top-down” and “bottom-up” elements, the Agreement has achieved near-universal participation, and has the potential to facilitate rising global ambition. The Agreement’s success will hinge in part on further decisions to be taken by Parties to elaborate the Paris architecture. This report outlines the emerging contours of key elements of this Paris ‘rulebook.’ The report is informed by a series of informal discussions among senior climate negotiators from a diverse group of countries. It was prepared and is presented by the Center for Climate and Energy Solutions on its own behalf.