Parental care of unrelated young is occasionally misdirected and maladaptive from an individual fitness perspective (e.g. interspecific brood parasitism). Alternatively, adults may‘adopt’dependent young and gain direct benefits irrespective of the degree of relatedness. For social species whose fitness is partially a function of group size, direct benefits of increasing group size may provide a mechanism favouring adoption independently of the inclusive fitness consequences. African wild dogs. Lycaon pictus, are social carnivores for which group size has been positively crrelated with reproductive success and competitive ability. Co-operative breeding by wild dogs has been described previously as strongly kin-selected and helpers were assumed to be invariably closely related to offspring. However, observations from this study show that the assumption that helpers are related to those they help is not always valid. A minimum of 25% of study area packs (n=12) contained nonbreeding adults that provided parental care for unrelated pups. Costs of adopting unrelated weaned wild dog pups are slight or nonexistent except for delayed costs due to later potential conflict with mature same-sex adoptees over access to mates. Immediate and delayed direct benefits identified here are associated with increasing group size and may indicate important mechanisms underlyig adoption and the evolution of helping behaviour in wild dogs.