BackgroundThe treatment of anxiety and depressive symptoms following acquired brain injury is complex and more evidence-based treatment options are needed. We are currently evaluating the BrainACT intervention; acceptance and commitment therapy for people with acquired brain injury.RationaleThis paper describes the theoretical underpinning, the development and content of BrainACT. Acceptance and commitment therapy focuses on the acceptance of feelings, thoughts and bodily sensations and on living a valued life, without fighting against what is lost. Since the thoughts that people with acquired brain injury can experience are often realistic or appropriate given their situation, this may be a suitable approach.Theory into practiceExisting evidence-based protocols were adapted for the needs and potential cognitive deficits after brain injury. General alterations are the use of visual materials, summaries and repetition. Acceptance and commitment therapy-specific adaptions include the Bus of Life metaphor as a recurrent exercise, shorter mindfulness exercises, simplified explanations, a focus on experiential exercises and the monitoring of committed actions. The intervention consists of eight one-hour sessions with a psychologist, experienced in acceptance and commitment therapy and in working with people with acquired brain injury. The order of the sessions, metaphors and exercises can be tailored to the needs of the patients.DiscussionCurrently, the effectiveness and feasibility of the intervention is evaluated in a randomised controlled trial. The BrainACT intervention is expected to be a feasible and effective intervention for people with anxiety or depressive symptoms following acquired brain injury.