More than half of the known languages that were spoken in Australia at the start of European colonisation are still used today, but three-quarters of them are severely or critically endangered. Failure to arrest these declines could mean that the vast majority of surviving Aboriginal and Torres Strait Islander languages will no longer be spoken within the next 30 years. The intergenerational transmission of language (in which children learn languages from their parents and/or grandparents) is one of the key mechanisms through which such declines may be reversed, but only about half the number of indigenous children whose parents speak an indigenous language also speak or are learning that language. In this paper, I analyse the results of the Longitudinal Study of Indigenous Children (LSIC) to identify the major protective and risk factors that influence the successful intergenerational transmission of indigenous languages within Aboriginal and Torres Strait Islander families. Results indicate that parent’s language proficiency and patterns of use are critical to successful language transmission as are the characteristics of the communities in which children live. Lessons and implications for the successful preservation of Australia's linguistic diversity are discussed.