Formal population policies are now common in sub-Saharan Africa, particularly to directly facilitate fertility decline. They tend to be underpinned more by ideology that by systematic data collection and analysis. A case study of policies to promote fertility decline in Kenya, where fertility has fallen substantially in recent years, illustrates how population data, particularly from the 1989 and 1993 Demographic and Health Surveys, have been used by government and international agencies to validate rather than to inform official policies.