Cities can use a range of principles and approaches to integrate the environment in urban planning and management. This report is intended to encourage and support urban decision-makers in this process. It starts with recognizing that action taken in towns and cities is essential for addressing global environmental problems. It accepts that, with an increasing proportion of the world’s population living in urban areas in low- and middle-income countries, these are important sites for engaging with the environment. The report describes the social and economic benefits that can be generated by addressing environmental challenges, and provides convincing evidence to support engagement with these issues.