The twenty-first Conference of the Parties (COP21) to the UN Framework Convention on Climate Change (UNFCCC) in Paris was a good COP in contrast to COP15 in Copenhagen, which will remain in history as the low point in climate policy. COP21 demonstrated unprecedented global collaboration when divisions were deep and stakes were high and resulted in the Paris Agreement, the first legally binding document to articulate a clear global temperature goal and a commitment to reach global net-zero emissions after 2050. The agreement is also universal, with developed and developing countries alike expected to act. This article outlines key outcomes and explains what led to the shift from a bad to a good COP. It also examines the threats and opportunities as the world moves from making commitments to implementing them and draws parallels to the global agenda-setting process on sustainable development that is also unfolding in the United Nations at the same time.