Small- to medium-sized native mammals have vanished from most of southern and arid Australia, primarily due to predation by feral cats and foxes. These species were often very abundant prior to European settlement and participated in a number of important ecological processes, including the dispersal of seeds and fungal spores, herbivory, predation and soil engineering. The loss of these species has likely had profound consequences for Australian ecosystems. The reintroduction of threatened mammals to feral predator-free islands and fenced ‘mainland islands’ has been an important tool in conservation in Australia for several decades. Australian Wildlife Conservancy (AWC), a not-for-profit organisation, is a leading exponent of this approach in Australia. Currently, AWC operates one island and four ‘mainland island’ reintroduction projects, ranging in size from 275 ha to 8,000 ha. These projects support populations of 11 threatened mammal species, including 90% of the global population of bridled nailtail wallaby, 30% of numbat and 10% of greater bilby populations. AWC is currently planning another four ‘mainland island’ reintroduction projects, ranging in size from 2,000 ha to 60,000 ha. When complete, AWC’s network of reintroduction projects aim to support secure populations of 19 threatened mammal species, substantially increasing global population sizes of many of these species. In this talk, I review the contribution of reintroduction projects to the conservation of Australian mammals and the restoration of Australian ecosystems. I consider three key issues: the value of reintroduction projects for conservation, the lessons learnt from existing projects and future directions for reintroductions.