New micro-level data have recently become available for three provinces of the The Netherlands for the period 1812-1912, which allow the study of the evolution of socio-economic differentials in infant and childhood mortality. The authors found significant differences in the levels of infant mortality by social group between the three provinces, and a wide variety in the pattern of social inequality. This showed the importance of the regional environment for the level of infant mortality in the nineteenth century. Contrary to expectations, strong social differences were also observed in neonatal mortality. Being born in an urban environment did not have a strongeffect on survival during the first year of birth. © Economic History Society 2005.