Explosive urbanization in developing countries is overwhelming the formal private and public sector's capacity to provide even minimum water and sanitation infrastructure and services. This paper describes how some of these needs are being met by the informal sector and how nongovernmental organizations (NGOs) can act as intermediaries between the formal and informal sectors. To illustrate the author describes the case of informal housing sector in Central America and the United States Agency for International Development (AID) effort to provide funds to the Cooperative Housing Foundation (CHF), a US-based nonprofit nongovernmental organization. In informal housing sectors, individuals are living in poor conditions, often without authorization or ownership. With a grant from AID, the CHF offered money to various NGOs. The NGOs in turn loaned the money to low income individuals. The individuals then used the money to improve their dwellings or to pay for property or register it with the municipality in an effort to become less marginalized.