Climate Change and Cities (ARC3) is a Cambridge University Press publication that grows out of two years of collaborative efforts of a multidisciplinary team of 106 scholars representing 50 cities that form the Urban Climate Change Research Network. This is the first-ever-ongoing-scientific assessment of the state-of-the-knowledge on climate and cities that unbundles adaptation and mitigation concerns and provides urban policy options for transportation, energy, water, health, landuse, and governance, with cross-cutting-city case studies.