Urban living is the new reality for the majority of the world's population. Urban change is taking place in a context of other global challenges--economic globalization, climate change, financial crises, energy and food insecurity, old and emerging armed conflicts, as well as the changing patterns of communicable and noncommunicable diseases. These health and social problems, in countries with different levels of infrastructure and health system preparedness, pose significant development challenges in the 21st century. In all countries, rich and poor, the move to urban living has been both good and bad for population health, and has contributed to the unequal distribution of health both within countries (the urban-rural divide) and within cities (the rich-poor divide). In this series of papers, we demonstrate that urban planning and design and urban social conditions can be good or bad for human health and health equity depending on how they are set up. We argue that climate change mitigation and adaptation need to go hand-in-hand with efforts to achieve health equity through action in the social determinants. And we highlight how different forms of governance can shape agendas, policies, and programs in ways that are inclusive and health-promoting or perpetuate social exclusion, inequitable distribution of resources, and the inequities in health associated with that. While today we can describe many of the features of a healthy and sustainable city, and the governance and planning processes needed to achieve these ends, there is still much to learn, especially with respect to tailoring these concepts and applying them in the cities of lower- and middle-income countries. By outlining an integrated research agenda, we aim to assist researchers, policy makers, service providers, and funding bodies/donors to better support, coordinate, and undertake research that is organized around a conceptual framework that positions health, equity, and sustainability as central policy goals for urban management.