How will the world's developing cities become vibrant-capable of meeting the climate, social, and economic challenges of tomorrow? Vibrant cities offer firms and households high expectations for good returns on investments, for a sustainable and resilient future, and for dynamic and inclusive growth. Cities thrive not only by increasing incomes and wealth for a select few but by improving common welfare through the equitable provision of basic services and opportu¬nities. To do this, tomorrow's vibrant cities will be: 1.Resilient and low carbon-Limiting greenhouse gas emissions, reducing vulnerability to climate related hazards, and rebounding from disasters and pandemics. 2.Inclusive-Meeting basic needs for all residents, while enabling all to aspire realistically to a bet¬ter life through investment in skills and through equitable access to job opportunities. 3.Productive-Driving economic growth, creating jobs, boosting incomes, and financing critical social and infrastructure investments. The report provides new evidence, analysis, and policy insights to advance green, resilient, and inclusive urban development-drawing on the latest thinking in spatial urban development and public economics. While spotlighting the Middle East and North Africa region (MENA), it offers general insights for city and country leaders around the world. In doing so, it lays the foundations to shore up our technical assistance and policy engagements for urban development in MENA and elsewhere through a new policy framework-inform, support, and protect.