The effects of brain injury are vast and disabling and the full impact of injury is often not observed until several years later. Yet the full scope of the long term difficulties people may experience (particularly after mild brain injury) and how multiple injuries affect recovery is unknown. This study aims to characterise the long-term effects of brain injury in New Zealand. Adults and children assessed as having a brain injury in a previous study (N=577) and who were followed up for one-year, will be assessed four-years later to measure any long-term effects on their cognitive functioning, emotional well-being and ability to participate in everyday activities. We will also find out whether participants experienced any additional brain injuries. By identifying who is at highest risk of recurrent injury and determining what facilitates or hinders recovery, we can identify the best ways to prevent injury, optimise treatment and maximise long-term recovery.