This report assesses South Asia’s progress in realizing the immense potential of its cities for promoting prosperity and livability. Using innovative nighttime lights data, as well as a host of other data sets, it examines how the region’s cities and subnational areas are performing and provides new evidence on the nature of urbanization in the region. In particular, the report documents a process of “messy” and “hidden” urbanization. Messy urbanization is reflected in the widespread existence of slums and sprawl, and hidden urbanization is seen in the large share of the region’s population that lives in settlements that possess urban characteristics but do not satisfy the criteria required to be officially classified as urban. The report describes the often severe stresses brought about by growing urban populations on infrastructure, basic city services, land use, housing, and the environment.Finally, the report discusses how best to ameliorate and manage those stresses. It identifies urban governance and finance as keys to the successful realization of the potential of South Asia’s cities.