From the beginning, the landscape has determined where and how people live. Over time, people embellished the natural landscape with an infrastructure of roads, aqueducts, bridges, ports, power plants, and more. Now communities are turning their attention to the central planning challenge of our time: sustainability. And they are discovering, or rediscovering, the benefits of green infrastructure—infrastructure that takes advantage of the natural landscape. The authors present six principles for successful green infrastructure projects.