The contrasting histories and political ecologies of two U.S. cities-Portland Oregon and Phoenix Arizona-shed light on their ability to learn from and influence the climate governance of their peers. Portland's populace, political leadership, and business sectors are motivated by environmental and social values , resulting in a collective sense of responsibility for fixing global problems like climate change. The city's pioneering land-use policies, green infrastructure, and multimodal transportation systems solidify its place at the climate action forefront. In contrast, libertarian Phoenix prioritizes real estate, efficient government, tourism, and protection of individual rights-the antithesis of Portland's altruism. However, because Phoenix's economic success depends on reliable supplies of water, power, and clean air, it has become an "accidental" expert in dealing with many of the worst effects of climate change: drought, heat island, and air pollution. Portland and Phoenix show that cities' reputations as environmental leaders or laggards may not reflect their ability to teach or learn. Rather, opportunities for urban climate governance learning depend on affinities between cities' political-ecological profiles. These examples illustrate how urban les son-learning and policy mobility, originally developed for cases where cities compete, can accelerate around issues like climat e change, where cities seek to cooperate.