Objective: To evaluate the course and identify determinants of community integration for up to 3 years following moderate to severe traumatic brain injury. Design: Prospective cohort study. Patients: A total of 119 patients with moderate to severe traumatic brain injury aged 16-67 years. Methods: The Community Integration Questionnaire was completed at 3, 6, 12, 18, 24 and 36 months post-injury. Repeated measures analysis of variance was performed to determine changes over time in the Community Integration Questionnaire and its subscales. Bivariate and multivariate regression analyses were used to identify determinants of community integration 36 months post-injury. Results: Compared with pre-injury, mean home integration, social integration, productivity, and total questionnaire scores decreased 3 months post-injury. Patient scores showed maximal improvement during the first year post-injury. Mean home integration, productivity, and total scores increased to a lesser extent during years 1-3 post-injury. Age, Barthel Index scores, hospital discharge destination, and pre-injury community integration scores were the major determinants of community integration 36 months post-injury (R-2 = 60%). Conclusion: After an initial decline, mean community integration scores gradually improve following moderate to severe traumatic brain injury. Understanding the course and determinants of community integration is necessary in order to determine functional prognosis following traumatic brain injury.