The Mumbai Climate Action Plan (MCAP) outlines pathways for the city of Mumbai to address climate vulnerability and reduce greenhouse gas emissions. Developed through participation in the international C40 Cities Climate Leadership Group and written by the Mumbai office of the World Resources Institute India (WRI), the MCAP suggests making ‘climate action’ a routine part of urban planning and governance. Despite political instability, WRI staff worked with municipal officials on governance-focused implementation, surpassing similar efforts in India and internationally. I consider the factors that contributed to this unlikely progress. Based on two years of ethnographic research, I outline how WRI staff, positioned at the intersection of the global field of urban climate action and the local field of Indian urban governance, acted as brokers between the urban government and C40, translating C40 best practices into locally amenable implementation steps. I argue that by layering novel climate policies derived from global norms atop existing governance structures, WRI staff encouraged the formalization of a climate-focused agenda within an otherwise intransigent governance setting. While longer-term outcomes of the MCAP remain uncertain and deeper change is still needed, this case demonstrates the possibility of establishing a foundation that could eventually make climate a routine aspect of urban governance.