In this study we examine broad-scale factors affecting the distribution of the yellow-bellied glider (Petaurus australis australis) in the southern Australian state of Victoria. Using the bioclimatic analysis and prediction system, BIOCLIM, and vegetation-suitability mapping, we assessed the potential distribution of the species at the time of European settlement and compared it to the current distribution. BIOCLIM revealed that P. a. australis is most likely to occur in areas with mean annual rainfall >600 mm and mean annual temperature between 6°C and 14.5°C. Much of its current distribution is skewed to the eastern half of the State, and our results emphasise a disjunction between western and eastern Victorian populations that is attributed to unsuitable climate and vegetation for the species. This indicates that P. australis in the west was most likely separated from eastern Victorian P. australis long before European settlement. Our results also indicate that isolated P. australis populations in south-western Victoria represent fragments of what was probably a much more widely distributed population when European settlement took place. Owing to the highly restricted distribution of suitable remnant native vegetation, these westernmost P. australis populations should be a high priority for future research and conservation work.