THIS IS A detailed report and analysis of findings from a household survey from a representative sample of the inhabitants of Nairobi’s informal settlements carried out in 2000. It reports on the demographic and health problems facing this population – who represent around half of Nairobi’s two million or so inhabitants. It was designed so as to provide data that was comparable to the 1998 Kenya Demographic and Health Survey and thus to show how conditions in these informal settlements compare with the rest of Kenya’s population. It presents detailed findings on the demographic, economic and social characteristics of households (including fertility levels and factors that influence these, infant and child mortality, maternal and child health, HIV/AIDs and other sexually transmitted diseases and social and health profiles of adolescents). The findings from this demonstrate just how poor living conditions and health outcomes can be among the poorer populations of large cities – and how these can be hidden by aggregate statistics for cities. Aggregated statistics for Nairobi for, for instance, infant or child mortality rates, are significantly lower than the national average or the rural average, but this is largely because of the concentration of middle and upper income groups within Nairobi. The report shows just how high infant and child mortality rates are in Nairobi’s informal settlements. This report is an example of a new generation of household surveys that focus on particular cities to show the scale of deprivation and disadvantage within them and who is most affected.