Sandhill dunnarts (Sminthopsis psammophila) are poorly understood, endangered marsupials. This research examined a Western Australian Great Victoria Desert (WAGVD) population. Methods comprised MaxEnt modelling, nocturnal radio- (n = 10) and GPS-tracking (n = 3), χ2 evaluation of shelter and random Minimum Convex Polygon (MCP) quadrats, habitat preference and diet analyses. S. psammophila were predicted to occur over a wide area in the semi-arid southern WAGVD. 77% of diurnal shelters were burrows, 19% in spinifex and 4% in logs. Burrow entrances predominantly faced north, had uniform dimensions (but variable depth) and were often concealed under spinifex. 97% of shelters were in interdune swales or dune foot slopes, dominated by Triodia desertorum and Aluta maisonneuvei. Shelter quadrats had significantly less canopy and litter, and more sand and spinifex, though no difference in spinifex age compared with random plots. Mean foraging MCPs and 90% clusters respectively were: males - breeding, 176 ha and 64 ha, and non-breeding, 42 ha and 15 ha; females - breeding, 24 ha and 8 ha, and non-breeding, 26 ha and 11 ha. Foraging was not random; north dune foot slopes were preferred. Breeding males quickly crossed several dunes, whereas females and non-breeding males foraged close to shelter cores. Mean dusk-to-dawn foraging time was 91.3%. Diet during the non-breeding season largely comprised small insects; during breeding, scats contained bigger prey, including skinks. In conclusion, S. psammophila is an active, spatially organised, opportunistic insectivore and carnivore, requiring large composite dunefield habitats. Conservation priority should focus on the southern WAGVD.