Adopted at the Millennium Summit in 2000, the United Nations Millennium Declaration recognizes the dire circumstances of the world's poor and disadvantaged. Its concomitant Millennium Development Goals (MDGs) articulate the commitment of Member States to tackle poverty, hunger and HIV/Aids, as well as to improve maternal and child health, education, gender equality, institutional partnerships and environmental sustainability. Environmental sustainability is addressed by MDG 7. UN-Habitat has served as focal point for the achievement of two of its component Targets. Target 7C aims to halve the proportion of the population without sustainable access to safe drinking water and basic sanitation by 2015. Target 7D aspires to improve the lives of at least 100 million slum dwellers by the year 2020.

In general, progress towards achieving the MDG targets has been slow and uneven. Some targets may not have been sufficiently ambitious whilst others may have failed to take into account important differentiations between countries' respective capacities. For its part, UN-Habitat has played a significant role in enabling cities to meet Target 7C on schedule and Target 7D ahead of schedule. Already, as of 2012, the lives of more than 200 million slum dwellers had been significantly improved. However, demographers had seriously underestimated the dynamism of urban growth and magnitude of demographic expansion. During the same time, 100 million new slum dwellers swelled cities' ranks. In retrospect, formulating this target in terms of absolute numbers rather than the overall proportion of a dynamic and changing total was problematic.

As the newly-constituted Open Working Group and its adjunct UN Technical Support Team deliberate the set of Sustainable Development Goals (SDGs) that will replace the MDGs when they expire in 2015, they will take these lessons of formulation into account. At the conference Making Slums History: a Worldwide Challenge for 2020, in Rabat, more than 20 Member States emphasized the positive role of urban planning and sustainable urban configuration. The resulting Rabat Declaration also acknowledged UN-Habitat's role in promoting this agenda and supported the establishment of a broad set of goals on cities and slum eradication. In this context, UN-Habitat has proposed an SDG on sustainable cities and human settlements. See UN-Habitat's Proposed Sustainable Cities SDGs.