What makes a great city? It is a pressing question because by 2030, 5 billion people—60 percent of the world’s population—will live in cities, compared with 3.6 billion today, turbo-charging the world’s economic growth.1 But for the leaders who govern cities, the challenges are tough. Those in many developing nations have to cope with urbanization on an unprecedented scale. Those in developed nations, where growth prospects are weaker, wrestle with aging infrastructure and stretched budgets. All are fighting to secure or maintain their competitiveness and hence the livelihoods of residents. All are conscious of the quality of life enjoyed by present citizens. And all are aware of the environmental legacy they will leave citizens of the future if they fail to find more sustainable, resource-efficient ways of expanding their local economies and managing their cities. A city’s performance has to be measured in a way that reflects all of these concerns—the strength of the economy, social conditions, and the environment. Various studies have looked at these three measures of performance either separately or together, and ranked cities accordingly.2 But while such studies can help us understand the elements of a great city, they do not tell us what city leaders actually do to make their cities great. What drives a city’s performance? Moreover, an absolute measure of performance can overlook the fact that each city has a different starting point; a relatively low ranking for a city that had an extremely low starting point would mask the efforts and innovations that helped such a city make significant progress. Therefore, to understand performance, it is important to consider not only current measures but also the trajectory of change. With this in mind, we undertook the research presented in this report. We developed and analyzed a comprehensive database of urban economic, social, and environmental performance indicators, interviewed 30 mayors and other city leaders in city governments on four continents, and synthesized the findings from over 80 case studies that sought to understand the steps city leaders had taken to improve a whole range of processes and services, from urban planning to financial management and social housing (see sidebar “About the research”). Whatever their starting positions, cities can change. Singapore’s rise from a colonial harbor to a world-class city in just a few decades and New York’s turnaround from the economic decline of the late 1960s and ’70s are just two examples. The wide range of measures city leaders in our research used to drive change makes it hard to assess the impact of each measure quantitatively. Yet some common themes emerge. Leaders who make important strides in improving their cities, no matter their starting point, do three things really well: they achieve smart growth, do more with less, and win support for change (Exhibit 1, previous page). This report describes some of the managerial practices that enable leaders to do these things successfully.