Most population growth in the twenty-first century will occur in the urban areas of the developing world, which are expected to increase by 2 billion inhabitants between 2000 and 2030. Urban living poses environmental hazards, which affect the current population, and especially the poor, through immediate, local impacts on health and safety. It also causes environmental degradation, with longer-term, wider-area, and intergenerational consequences. Variations in the incidence and relative severity of a range of environmental problems across cities at different levels of development suggest differences in priorities for action. In coming decades, in order to support sustainable national development, urban areas will need to ensure a healthful and attractive environment for their rapidly expanding populations, while protecting natural resources and reducing harmful impacts on wider regions and later generations. The massive new investment in the capital stock of cities required for the doubling of urban population by 2030 will be critical to environmental outcomes. Using a number of city case studies, the course highlights local solutions, as well as new technologies for monitoring, planning, and managing urban growth.