The current article describes critical issues in adapting traditional group-treatment methods for working with individuals with reduced cognitive capacity secondary to acquired brain injury. Using the classification system based on functional ability developed at the NYU Rusk Institute of Rehabilitation Medicine (RIRM), we delineate the cognitive and interpersonal capabilities that differentiate group-participation capacity. An overview of the RIRM interventional process, including strategies of change (cognitive remediation versus psychosocial groups), is provided. Empirical support for the RIRM method of group assignment and treatment outcomes for our model is also referenced. (Contains 1 table and 2 figures.)