Both developed and less developed countries are becoming increasingly urbanized. The earlier industrialized countries have developed more infrastructure to support the building of healthy housing, in neighborhoods that are strongly linked to municipal and global health initiatives, but to some degree housing and neighborhood, issues vary only in degree between the developing and developed worlds. Overall, a billion people, a third of people living in urban areas, live in slums, where environmental determinants lead to disease. Although communicable diseases predominate in the developing world and have reemerged in the developed world, non-communicable diseases are also growing disproportionately in the developing world. At a global level, the Millennium Development Goals explicitly focus on an integrated approach to slum upgrading. The per capita cost of slum upgrading is almost twice the cost of providing new affordable housing at the outset. It is argued that to improve health and well-being in the slums we need to have interventions that reduce urban poverty in the broadest sense and improve the deficiencies associated with slums. There is an urgent need to scale up the best-practice interventions. Examples are given of successful local community initiatives that have been set up under national strategies in Tanzania and by Indian women collectives that are globally linked and have helped develop housing and sanitation improvements. The unit costs for such interventions are within the reach of all the key stakeholders.