The 2015 Paris Climate Conference (COP 21) that will be held in December represents a key step in the transition toward a low carbon world economy. The Conference is attracting much attention and the expectations are very high. Many countries, both developed and developing, are already moving toward a more sustainable growth through the adoption of “intended nationally determined contributions” to the reduction of greenhouse gases emissions, the so-called INDCs. INDCs include mitigation and adaptation measures to be implemented starting from 2020. The United States, China and the European Union will be key actors for the successful outcome of the Paris Conference and the actions that will follow. The commitments announced by these three powers in view of a future agreement are ambitious but quite different, as will be the financial efforts for technology and know-how transfer. The involvement of the private sector and the creation of a political and regulatory context favorable to investments and public-private collaborations is essential. Faced with these challenges, trilateral cooperation plays an increasingly important role, also in light of the new paradigm in transatlantic relations and in relations with China. Against this background, the Conference aims to provide an analysis of emission reduction goals and, in general, of the positions of EU, China and the US on the key topics of the Paris Conference.