The benefits of rehabilitation following acquired brain injury (ABI) are all too often disrupted by a lack of engagement in the process, variously attributed to cognitive, emotional and neurobehavioural sequelae, and prominently to impaired self-awareness of deficits. Motivational Interviewing (MI) has been widely applied to address treatment adherence in health settings, including a small but emerging evidence base in brain injury contexts. A conceptual review of the literature is offered, examining the interplay of neurological and psychosocial determinants of engagement difficulties after ABI, and discussing the possibilities and limitations of MI as a therapeutic strategy to enhance motivation. The theoretical bases of MI are outlined, focusing particularly on the transtheoretical stages of change model and self-determination theory. The converging evidence suggests that the guiding philosophy and principles of MI - characterised by non-confrontation, collaboration and self-efficacy - might help to foster readiness for participation in rehabilitation. A dynamic motivational model of engagement is presented, identifying MI's potential contribution in three key areas: firstly, to set the stage for therapeutic alliance and case formulation; secondly, to facilitate acceptance of deficits and realistic goal-setting; and thirdly, to promote constructive engagement in the range of clinical interventions that comprise a holistic neurorehabilitation programme.