This collaboration between an American scholar-official and a Chinese counterpart seeks to demystify how their respective governments make and execute policy and explores the two countries’ differing motivations, procedures, and constraints. The authors focus on environmental policy, especially the 2014 agreement between China and the United States, the two largest emitters of greenhouse gases, that set out a joint plan to mitigate climate change by 2030. The deal, which included China’s first-ever commitment to halt the growth of its emissions, made possible the Paris agreement on climate change the following year. U.S. President Donald Trump has pledged to withdraw the United States from the Paris agreement (a decision that will take effect in late 2020), but in the decentralized United States, the effect of the withdrawal will be muted, as over two-thirds of the states and many cities, probably with the support of a majority of U.S. citizens, will carry on with their climate change policies.