This chapter focuses on how urban development relates to coastal flood risk. It begins with key concepts related to coastal geomorphology and flooding in river deltas and estuaries (e.g., processes of landscape formation, protective benefit of wetlands, storm surge, human impacts on coastlines). It then presents the urban development and flood histories of New Orleans (including Hurricane Katrina) and New York City (including Hurricane Sandy). The cases are assessed and compared using the Urban Risk Dynamics framework. Both demonstrate how urbanization in coastal cities often entails extensive loss of wetlands, construction of navigational waterways that inadvertently funnel storm surge, and floodplain expansion through land subsidence or building out the waterfront. Urban expansion into more hazardous lands may be intentionally enabled through construction of flood protection structures. Generally, the least economically valuable land was occupied by the most socially vulnerable populations. Catastrophic events like Hurricanes Katrina and Sandy spur mitigation but reinforce ongoing urbanization trends. Lower density areas, however, provide opportunities for strategic retreat.