The Climate Impacts Decision Support Tool (CIMPACT-DST or tool) is an easy-to-use Excel-based decision support tool for urban planners and project developers. Cascadia Consulting Group, Inc. (Cascadia) initially developed CIMPACT-DST for the City of Seattle. In 2012, the United States Agency for International Development (USAID) expressed an interest in customizing CIMPACT-DST for use in Vietnam. Vietnam’s significant climate exposure and relative abundance of existing climate change studies and projects presented a promising environment for customizing CIMPACT-DST to help turn more of that information into adaptation action on the ground. From 2012 to 2015, under contract to USAID’s Global Climate Change Office and working under the Climate Change Resilient Development project, Cascadia customized and deployed CIMPACT-DST in a pilot city and subsequently for use across the country’s 760 cities and 63 provinces. The tool supports systematic integration of climate change considerations into urban planning and land-use decision-making, with the ultimate goal of building resilience in Vietnam to climate change impacts like sea level rise and increased flooding.