Urban areas are on the rise and changing rapidly in form and function, with spillover effects on virtually all areas of the Earth. The UN estimates that by 2050, 68% of the world's population will reside in urban areas. In the inaugural issue of npj Urban Sustainability, a new Nature Partner Journal out today, a team of leading urban ecologists outlines a practical checklist to guide interventions, strategies, and research that better position urban systems to meet urgent sustainability goals.