The Mumbai Slum Sanitation Program:Partnering with Slum Communities forSustainable Sanitation in a Megalopolis. The city of Mumbai (formerly Bombay) in India has undergone metamorphic changes over the years, because of the rapidpopulation growth and changing character of the city’s economy and socioeconomic composition. The challenges involved inproviding basic services, particularly adequate housing and related infrastructure, are enormous. Sanitation especially posesdaunting challenges since more than half of the city’s population of 13 million, that is, 6.3 million people, live in some 2,000densely populated slum settlements. In these slum settlements, residents have to largely depend on public toilets provided bythe government. These sanitation facilities are poorly maintained for the most part, and thus cause serious public health andenvironmental risks for the entire population of the city. An estimated one in 20 people in these slum settlements are compelledto perform daily ablutions and relieve themselves in open areas. Insecurity of tenure, complex land ownership patterns, technicalproblems, and other constraints pose formidable obstacles to strategies and programs that aim to address the problem.