Theoretical and research literature on the role of fathers in child development is reviewed. The first section points out that there is little known about father-infant interaction, and the impact of the father on infant social development, though diverse theoretical perspectives all assume that the father’s role is minimal, and, at best, indirect. It is suggested that this assumption is unsubstantiated. Fathers are believed to play an influential role in later child development, though the theoretical assumptions, again, are inadequately validated by research. A new hypothesis is proposed whereby fathers are seen as playing a vitally important role in socialization, yet one which is qualitatively different from that played by mothers. Various research designs are suggested whereby this hypothesis can be subject to empirical validation.