Aggression can have a critical impact on the functioning of societies. Some aspects of aggression have received considerable attention, such as links between parenting behavior and offspring aggression in humans. Although acknowledged as being important to the understanding of human aggression, animal aggression has been relatively unstudied. Recent mammalian animal research is emerging that addresses issues relevant to the study of parenting and aggression. This has been accomplished primarily by focusing on nontraditional mammalian model systems. We integrate human and nonhuman animal studies to (a) further elucidate the potential impact that the behaviors of fathers have on offspring aggression, (b) study the influence of paternal behavior on the behavior of offspring and transfer of aggression across generations, and (c) explore neural and physiological underpinnings for variation in paternal behavior and aggression.