This lecture examined the effects of urban design on health, placing it in the larger context of planning and public health, and proposed solutions that combine public health and urban planning strategies relevant for the 21st century. Dr Frumkin spoke of public health lying at the heart of urban planning in the early 20th century, but since then, the growth of cities has occurred in relatively unplanned ways. Urban sprawl - the expansion of cities into rural areas, heavy reliance on automobiles, low-density, low-mix land use patterns - represents one extreme, especially in North America and Australia, but increasingly in Europe as well. At the other extreme we have high density, overcrowded, creaking infrastructure. Frumkin described how urban planning and design may affect health in a variety of ways: threatening air quality, impeding physical activity, increasing injury risks, and eroding social capital are but a few examples.