The Lancet commissioned a cross-Faculty UCL working group to provide an analysis of how health outcomes are part of the complexity of urban processes. The report argues against a simple ‘transitions model’ that assumes that outcomes they will improve with economic growth and demographic change. Instead, it highlights the role that urban planning can and should play in delivering health improvements through reshaping the urban fabric of our cities. It considers this through case studies of sanitation and wastewater management, urban mobility, building standards, the urban heat island effect and urban agriculture. It follow this with a discussion of the dynamic and highly politicised processes of planning in cities and then develop recommendations based on a dual appreciation of urban citizens’ core entitlements and the potential for the progressive realisation of their right to a healthy urban environment.