The proportion of the global population living in cities and towns is expected to rise from 54 per cent in 2015 to 66 per cent by 2050, which will result in a significant expansion of existing cities, as well as the construction of new cities. Without a new approach to urbanization, material consumption by the world's cities will grow from 40 billion tonnes in 2010 to about 90 billion tonnes by 2050. Therefore, the resource use implications and environmental impacts of urbanization are significant. Resources should now become a central policy concern, in addition to concerns about climate change. We have a once-in-a-lifetime opportunity to shift this expected urbanization on to a more environmentally sustainable and socially just path. Decisions made today on urbanization and land-use models, as well as on critical infrastructure, will determine whether our investments are future-proof, or whether they lock us on to an unsustainable path. This report calls for a new strategy for 21st Century urbanization, and presents the parallel actions on urban planning, sustainable design, resource-efficient components, and infrastructure for cross-sector efficiency that are required for a transition towards low-carbon, resource-efficient and socially just cities, It also presents the new governance model and the politics of the new imaginative business propositions and experimentation that will make the transition possible.