Translocating species to areas where significant threats have been removed or ameliorated is an important conservation tool. Two types of translocation are (1) reintroductions, where locally extinct species are re-established and (2) introductions for conservation purposes. In areas where the previous mammal fauna assemblage is poorly understood, remains can provide evidence of the species originally present; information that is integral to planning and justifying translocations. Evidence of 3 mammals was found on Faure Island, but species-area relations of other northwest islands indicate the carrying capacity of Faure is 8 species. Both aspects were taken into account when planning translocations. Four species were successfully translocated to Faure, two as reintroductions (Pseudomys fieldi, Perameles bougainville) and two as conservation-motivated introductions (Lagostrophus fasciatus, Bettongia lesueur). Bettongia lesueur was selected instead of B. penicillata, previously present, due to its higher conservation concern. The previous presence of a Bettongia species suggested that the habitat may be suitable for B. lesueur, which is now well established. Evidence of 20 non-volant mammals was found at Mt Gibson; 9 of these were subsequently selected for reintroduction. The now extinct Leporillus apicalis was confirmed as a former inhabitant, providing impetus for the inclusion of L. conditor in the restoration program. Although the program at Mt Gibson is in its infancy, the species translocated so far are establishing satisfactorily. Understanding of the composition of previous faunal assemblages enables translocation programs to re-establish communities of species and make more informed decisions about the suitability of areas for introductions for conservation purposes.