The cognitive reserve hypothesis has been proposed to account for the mismatch between brain pathology and its clinical expression. The aim of the current research was to explore, in a longitudinal data set, the effects of level of educational attainment before brain injury (cognitive reserve) and clinical factors on the level of rehabilitation-induced changes in disability and community integration. Participants in receipt of postacute rehabilitation were assessed at induction to the service and again at between 14 and 18 months of follow-up while still in service on changes in aspects of their abilities, adjustment and participation (Mayo Portland Adaptability Indices) and community integration (Community Integration Questionnaire). Controlling for type and severity of injury, age at onset of injury and duration of time since injury, participants with higher previous educational attainment showed significantly greater changes over the course of rehabilitation on adjustment to their injury and participation, but not on abilities, or community integration following postacute rehabilitation. Level of education would appear to be an important element of cognitive reserve in brain injury that serves to aid responses to postacute rehabilitation in terms of an individual’s adjustment to disability and participation.