A combination of fires and logging mean that more than 80% of the montane ash forests inhabited by Leadbeater’s possum (Gymnobelideus leadbeateri) in the Victorian Central Highlands consist of ecologically young stands possessing few trees with hollows. As a consequence, there have been predictions of a substantial decline in Leadbeater’s possum populations over the next 40 years. If this is to be averted, or reduced in extent, then an immediate means of increasing den site availability for the species is required. The results of a recent investigation into nest-box use by the species in lowland swamp forest demonstrate that high rates of occupancy can be achieved by targeting established colonies at sites where the vegetation structure is suitable for box installation. This suggests that nest boxes can be an effective means of increasing den-site availability for the possum, and therefore have considerable potential to contribute to the species’ conservation in the short term. Such measures should be applied in conjunction with altered forestry practises that better provide for the retention and future provision of mature hollow-bearing trees.