Coastal reclamation, the process of creating land by infilling coastal waters or wetlands, offers a possible bulwark against rising sea-levels associated with climate change. Yet, reclamation also demands wrenching distributional trade-offs that often favor developers and property owners over poor fishing communities. As a result, battles over reclamation have erupted in dozens of Indonesian cities in recent years. In this paper, I propose a theory to explain variation in the effectiveness of anti-reclamation movements. I argue that geographically and economically diverse coalitions are well-suited to mobilize mass demonstrations and coordinate voters to oppose reclamation, while local and class-based coalitions resort to litigation due to their relative weakness. Based on primary source documents, local news archives, and fieldwork in Makassar and Bali, my findings suggest that reclamation projects succeed when elite coalitions of politicians, developers, and local businesses bulldoze class-based opposition. Under such conditions, reclamation is likely to accelerate a process of “climate gentrification” in which climate change adaptations benefit the rich and deepen the vulnerability of the poor.