Pressing challenges in urban adaptation planning to extreme events include: (1) involving vulnerable populations in the impacted area; and (2) employing a multi-level stakeholder collaborative process to build consensus for action. These processes become even more important as adaptive urban planning is recognized as an effective governance model for adaptation to climate change. In a case study of a low to moderate income community vulnerable to present and increased coastal storm surge flooding, the Supported Community Planning Process was employed because (a) most residents of East Boston affiliate primarily with their own local neighborhoods and (b) the residents need targeted expertise to help them understand some of the scientific and technical aspects of adaptation planning. Collaboration was necessary among three sets of critical stakeholders interested in adaptation strategies in East Boston — the local residents and small businesses, the City of Boston, and the agencies that provide infrastructure services — because some adaptation actions will collectively protect assets of all. The overall process occurred successfully because of positive, knowledgeable, and direct exchange of values and goals. The research illustrates how marginalized populations can be effectively engaged in urban adaptation planning, and how that process can be combined in multi-level stakeholder collaborative planning so that plans might be developed that meet multiple shared and individual goals in a cost-effective manner.