Measuring and monitoring population size and growth are critical to assessing the progress and ultimately the success (or failure) of a reintroduction. The Woylie (Bettongia penicillata ogilbyi) is one of Australia's threatened critical weight range mammals. To increase the species' area of occupancy, extent of occurrence, number of sub-populations and global population size, in addition to creating a source population for future reintroductions, a new population has been re-established into a safe haven located within the species' former range – Mt Gibson Wildlife Sanctuary. In this paper, we document the first 3 years of the reintroduction programme, over which time 162 individuals were translocated to Mt Gibson. Specifically, we (i) provide information on survivorship, (ii) estimate changes in critical population metrics (density, population size and distribution) and (iii) look for any major habitat preferences. Survivorship of collared animals was complete (i.e. zero mortality). The most recent population estimate was in the order of 750 individuals, reflecting strong growth in population size and density. The woylie has occupied the majority of the safe haven and is well represented in all major vegetation communities. The translocation is on track to meeting the key success criteria: a self-sustaining population of woylies with a minimum of 300 individuals.