In this paper social relationships (as defined by Hinde) between age/sex classes of kangaroos, wallabies and rat-kangaroos are reviewed and characterized by frequencies, direction and, where possible, intensity of behavioural interactions, by their patterning in sequences and by distance
regulation. Male social organization in the wild for larger non-solitary species is organized in an age/size-related hierarchy. Frequent interactions among equal-sized males stabilize this hierarchy and large males by their simple presence deter younger ones from courting. Depending on
social organization in the wild, the presence of one or more males, sometimes males from different age classes, is desirable from the animal welfare standpoint. The structure of breeding groups can be greatly improved in terms of welfare and breeding optimization, when a diversity of social
relationships are as close to natural conditions as possible.