This paper presents an analysis of levels of life expectancy and their patterns of change among six socio-economically differentiated sub-populations of England and Wales for the period 1851-1911. Differences in mortality levels among these sub-groups and their rates of change are analyzed with respect to three groups of explanatory variables, viz., environmental, stratification and demographic variables. Their relative importance for different periods is assessed and discussed. The findings show consistency with two previous studies, which have suggested that medical advances had little effect on the increase in life expectancy during the second half of the nineteenth century. The present paper supports the results of one study in that public health measures affected life expectancies earlier, while subsequently, the increase in standards of living was more important.