Improving childhood vaccination coverage is a key health policy objective in Africa, and as availability increases, it will depend on addressing issues of demand and timely schedule completion. This paper explores vaccination demand in urban and rural areas of The Gambia as shaped by prevailing local vaccination cultures (comprising maternal knowledge and understandings, socio-cultural contexts and interactions with health providers). A survey of 1,600 mothers constructed on the basis of prior ethnography finds a high level of social demand for vaccination, based on lay theories of the general value of immunization in complementing traditional child protection practices. For most rural mothers, strong social networks encourage routine clinic attendance and vaccination 'default' arises only through day-to-day problems and contingencies. However, more pervasive patterns of schedule non-completion are found amongst poorer urban mothers, including recent immigrants, who experience social exclusion at infant welfare clinics. These findings point to the need for health education dialogue grounded in mothers' own understandings and for particular policy attention to improving the clinic experiences of vulnerable social groups in rapidly expanding urban areas.