Coastal cities are critical areas for global environmental change, but they have not been a focus of study in coastal zone management or urban planning. This paper lays the conceptual groundwork for such a focus, based on an ‘ecomanagement’ or ecosystem approach. The unique ‘bi-polar’ aspect of the juxtaposition of a complex natural system with a complex built system is stressed and explored. Among the benefits of an ecosystem approach is that it provides a common, scientifically defensible, ground for diverse visions and jurisdictions in a designated area. The history of recent ecosystemic and metabolic studies of cities is reviewed, as well as the implications of the intensification of use of the natural ecosystem for coastal city purposes. A series of brief case studies of developed and developing country cities is presented: Dakar, Hanoi, Alexandria, Toronto, and Venice. Finally, some of the implications of studying coastal cities in the context of rapid global change are outlined, as a preliminary agenda for further research.