Although a variety of behavioural mechanisms are known to inhibit infanticide in male house mice, the potential for social subordination to inhibit infanticide has not been widely investigated. Sixty male CF-1 stock house mice (Mus domesticus) were grouped five per cage from weaning until 5 months of age. Each male was then isolated and tested for infanticide at 1-day and 25-days after being singly housed. Only 13% were infanticidal after 1-day of isolation, but after 25-days of isolation, 44% were infanticidal (P < 0.0001). Thus, being group-housed with other males inhibits infanticide in most CF-1 male mice. From an ecological perspective, the cage-by-cage data suggest that subordination is a behavioural counterstrategy by which a dominant breeding male can inhibit his rivals from killing pups, thus maintaining social stability and reproductive success in a typical house mouse microdeme.