Healthy communities put people first, with safe housing, convenient schools and workplaces, and ready access to food, water, recreation and sustainable transportation. Rural or urban, resource-rich or impoverished, they offer opportunity and hope, and reward imagination and ingenuity. These places also foster a sense of shared purpose, perhaps sporting community centers and gardens, resource-sharing activities and microenterprise, sidewalks and bike lanes. What are the must-have features of a healthy community? How should small towns and large cities be designed in the future? What does the explosion of mega-metropolises around the world mean to health? Risa Lavizzo-Mourey, Gabe Klein, Kennedy Odede, Gina Murdock, Belinda Reininger