The effects of the pace of childbearing and breastfeeding practices on infant mortality have rarely been considered together. In this paper, we design and use a set of methodological tools to test a variety of hypotheses postulating the effects of breastfeeding and pace of childbearing on mortality in infancy and early childhood, the mechanisms through which those effects operate, and the contingencies that strengthen or weaken them. The strong effects of both length of breastfeeding and the pace of childbearing on the risks of child death suggest that neither of them exerts an impact on mortality totally mediated by the other. Social and demographic factors (such as age of child, education of mother, and region of residence) also condition the impact of breastfeeding and pace of childbearing on mortality.