The social organization and dynamics of a captive dingo (Canis familiaris dingo) colony was studied to understand behavioural mechanisms of population regulation. Dingoes developed into an integrated pack of 7 adults and one litter of pups. Other adults were surplus or were killed so that, of the potential 43 dingoes in the enclosure, only 16 survived after three years. Within the pack there were discernable, but not totally independent, male and female hierarchies where rank order was largely determined and maintained by aggressive behaviour. Most rank changes occurred during the breeding season and plasma Cortisol values suggested that the alpha and low ranking males exhibited the highest stress levels. All females became pregnant, but the alpha female killed all pups of all other females, despite being closely related. Although the structure and dynamics of dingo and wolf packs is largely similar, the major mechanism suppressing reproduction in dingoes is dominant female infanticide whereas in wolves dominants suppress copulation by subordinates. Some consequences of this reproductive strategy provide insight into the significance of the copulatory tie in canids and an additional explanation for the increase in dingo numbers in Australia since European settlement.