For the poorest people, low level of access to basic services is both a cause and a consequence of their poverty and deprivation. A set of interacting factors means that supply-side and demand-side problems deny them access to health, education, and water and sanitation services. Demand-side approaches to improving services (participatory planning, local health councils, and user groups) offer ways forward but these need to be matched by supply-side reforms (packaging services for the poorest, effective geographical targeting, regulation of private providers, public sector reform and increased public finance). While technical changes are needed, helping the poor to access the basic services they need must be embedded in longer-term processes of progressive social and political change.