In 2008, the Council of Australian Governments (COAG) agreed to a set of targets for 'Closing the Gap' in disadvantage between Aboriginal and Torres Strait Islander and non-Indigenous Australians. Currently, progress is difficult to measure accurately because Indigenous status is either missing or inconsistently reported across data sets. To ensure a consistent approach to dealing with Indigenous status reporting, COAG directed the Australian Institute of Health and Welfare and the Australian Bureau of Statistics to develop national best practice guidelines for linking data related to Indigenous people. This report offers guidance on how to derive Indigenous status when it is missing or inconsistently reported, in a way that protects privacy and individuals' right to self-identification.