We are living in the age of cities. It is an urgent time, and an uncertain one. Never before have human beings built so much with such haste. Yet we understand so little about how our urban world grows — and sometimes — declines. To meet this challenge, the world’s universities have set out to plug this knowledge gap, and establish a new science of cities. This report is an initial attempt to understand the collective scope and impact of this movement. What does this new science seek to achieve? Who are its practitioners? What questions are they pursuing? What methods do they use? What are they learning? How might their discoveries shape our shared urban destiny?