This article provides an explanation for how increased public participation can paradoxically translate into limited democratic decision-making in urban settings. Recent sociological research shows how governments can control participatory forums to restrict the distribution of resources to poor neighborhoods or to advance private land development interests. Yet such explanations cannot account for the decoupling of participation from democratic decision-making in the case of planning for climate change, which expands the substantive topics and public funding decisions that involve urban residents. Through an in-depth case study of one of the largest coastal protection projects in the world and drawing on global scholarship on participation, this article narrates the social production of resistance to climate change infrastructure by showing how the state sidestepped public input and exercised authority through appeals to the rationality of technical expertise. After a lengthy participation process wherein participants reported satisfaction with how their input was included in designs, city officials switched decision-making styles and used expertise from engineers to render the publicly-supported plan unfeasible, while continuing to involve residents in the process. As a result, conflict arose between activists and public housing representatives, bitterly dividing the neighborhood over who could legitimately claim to represent the interests of the "frontline community." By documenting the experience of participants in the process before and after the switch in decision-making styles, this article advances a sociological description of public influence in policy: The ability for participants in a planning process to recognize their own input reflected in finished plans.