Extensive research has established that fathers' engagement in parenting benefits children, but few studies have described how fathers contribute to child development even before birth. In this article, we consider both direct and indirect pathways through which expectant fathers shape child development during the prenatal period. Regarding direct pathways, we review work on expectant fathers' contributions to child development through genetic and epigenetic processes, as well as neuroendocrine mechanisms. Regarding indirect pathways, we outline ways in which expectant fathers indirectly influence child development through the couple relationship. In so doing, we seek to provide a foundation from which to formulate future lines of inquiry on the role of expectant fathers in child development. This research can inform clinical interventions and policies geared toward improving the early caregiving environment and child development.