Although not for the reason most climate watchers anticipated, the 15th Conference of Parties (COP) to the UN Framework Convention on Climate Change (UNFCCC) and the fifth Meeting of the Parties (CMP-5) to the Kyoto Protocol at Copenhagen marked an important moment in the history of the climate negotiations. Despite legally attracted 125 heads of state and government, and expended as much political capital, yet failed to deliver in quite so spectacular a fashion. And never before had outcomes been this dramatically misaligned with popular expectations. There are many lessons to be learned from the Copenhagen experience, both substantively and in terms of process.