Peter Marcotullio examines, in his chapter contribution, “The Asian urban energy system.” Asia’s economic growth has been associated with the massive movement of people to the region’s cities. From 1970 to 2010, approximately 1.36 billion people were added to urban areas across the region, bringing the urbanization level from 23.7 percent to 44.8 percent. Both economic growth and urbanization have driven and been driven by energy use and supply. With the expansion of economic activities and the building of cities in which much of this activity occurs, the region has increased its total energy supply from 4.4 to 12.7 Gigatons oil equivalents (Gtoe), almost a threefold increase. All three of these factors are tightly interlinked, although the details of how each has changed together are as varied as the geographies and cultures of the region. This chapter explores the overall trends, patterns and dynamics among Asia’s urbanization and energy supply and demand, using a systems approach in suggesting linkages between these patterns and those of economic progress. Peter Marcotullio first highlights both the overall dynamic change and the diversity among the region’s nations and cities, then points out the sustainable development challenges ahead, including meeting the goals of lowering energy-related pollution, providing universal access to modern energy and reducing greenhouse gas (GHG) emissions.