In this series of 8 papers, the AUS-TBI consortium describes the Australian approach used to select the common data elements collected acutely, that have been shown to predict longer term outcome following moderate-severe TBI across the lifespan. This paper presents the unified single data dictionary, together with additional measures chosen to facilitate comparative effectiveness research and data linkage. Consultations with the AUS-TBI Lived Experience Expert Group provided insights on the merits and considerations regarding data elements for some of the study areas, as well as more general principles to guide the collection of data and the selection of meaningful measures. These are presented as a series of guiding principles and themes. The AUS-TBI Aboriginal and Torres Strait Islander Advisory Group identified a number of key points and considerations for the project approach specific to Aboriginal and Torres Strait Islander peoples, including key issues of data sovereignty and community involvement. These are outlined in the form of principles to guide selection of appropriate methodologies, data management and governance. Implementation of the AUS-TBI approach aims to maximise ongoing data collection and linkage, to facilitate personalisation of care and improved outcomes for people who experience moderate-severe TBI.