This title includes a number of Open Access chapters. Because cities are such complex systems, creating sustainable urban environments is a challenging goal. No single strategy-or even several strategies-will be eugh to achieve tomorrow's healthy and sustainable cities. The challenges resist compartmentalization, because the factors intersect and overlap. The articles in this compendium were chosen to expand the understanding of these complicated issues in a n-linear way. The editor has selected research in the following topics: improving urban air quality; municipal solid waste alternatives; municipal water management; reducing urban energy consumption.