A green and just transition – i.e. concerted global and national efforts to achieve worldwide carbon neutrality by or around the mid-century globally, in an inclusive manner and adapted to each national context – requires an active co-operation of all countries, developed and developing. It also entails ensuring that no one is left behind, and offering support to those in need, including least developed countries (LDCs) and Small Island Developing States (SIDS). Guided by the preamble of the Paris Agreement, this report proposes ways for G20 and developing countries to enhance the coherence of their policies towards that vision, deepen their co-operation and render the international architecture better suited to the implementation of green and just transitions.