Social interactions are vital for the survival of the individual in many species. One form of social interaction, parental care, ensures the well-being and proper development of the young through manifestation of species-specific stereotyped behaviors. For example, in house mice, Mus musculus, parental care includes building of a nest, protecting, grooming and feeding of the offspring. Interestingly, most of these behavioral components are displayed by mothers, fathers, and unexperienced females, but not by virgin males. Similar to adults in many species known to kill their offspring, male mice display aggression and are infanticidal; they become paternal only after mating. The neuronal substrate of this fascinating phenomenon is poorly understood. I am interested in understanding the state-dependent interplay between the infant-directed aggression and the parental behavior, and in finding where and how the switch happens at a circuit level.