Cities around the world are undergoing two important transformations. First, they are growing. For the first time in history, a majority of the world’s population lives in urban areas. Second, they are beginning to evolve into “smart cities”—cities capable of collecting and analyzing vast quantities of data to automate processes, improve service quality, provide market signal feedback to users, and to make better decisions. While city governments can and should manage much of this transformation, national governments have an important role to play in accelerating and coordinating the development of smart cities. Indeed, the long-term success of smart cities in any particular nation will likely depend on whether the national government supports their development.