In this talk, Professor Bettencourt shows that cities and urban systems are the natural environments creating development. In this context, normative ideas of development acquire a new and more precise meaning, as the tangible expansion of physical, social, and economic connectivity and interdependence. He shows that this framework explains empirical patterns across time and diverse geographies and accounts for simultaneous changes across many distinct metrics, reconciling heterogeneity at the largest scale (nations) and the smallest (neighbourhoods) within a single coherent picture.