The spotted-tailed quoll (Dasyurus maculatus) is an endangered marsupial carnivore endemic to eastern Australia. A paucity of information on the dynamics of wild populations has hindered conservation of the species. The population dynamics of spotted-tailed quolls were investigated in an area of unusually high abundance in north-eastern New South Wales, where density is conservatively estimated at 0.3 km^-2. Sixty individual quolls were captured on 331 occasions over 22 months. Apparent survival, timing and rate of reproduction, and morphometric data were compared with those of quolls from other areas. Population models were employed to investigate patterns in the behaviour and apparent survival of quolls in the study area. The high abundance of D. maculatus identifies the study area as vital to the conservation of quolls on mainland Australia, and to the future study of the species.