PURPOSE: This study aimed to evaluate the effectiveness of an intervention based on the ICF 'Environment' dimension for enhancing the well-being and psychosocial outcomes of patients with acquired brain injury in an outpatient (day hospital) setting. METHOD: A mixed methodology cohort study comparing an intervention group with an historical non-intervention group using pre- and post-intervention and follow-up measures. The 6-week group intervention involved participants and their significant others. Pre- and post-intervention data from the intervention group and the non-intervention group were compared using 2 x 2 analyses of variance for five standardised outcome measures. Semi-structured interviews with intervention participants and significant others were used to provide qualitative feedback. RESULTS: A significant group by time interaction was found for level of community integration on the Sydney Psychosocial Reintegration Scale and depression scores on the Hospital Anxiety and Depression Scale, with greater improvements for the intervention group compared with the non-intervention group. No other significant differences between groups were found. Gains in community integration were maintained by the intervention group at 1-month follow-up. Qualitative feedback from participants indicated the value of: sharing experiences, the group content, goal setting, comparing with others and the group processes. CONCLUSIONS: The Environment-focused intervention was useful in improving patient outcomes in terms of better self-reported community integration.