Apathy commonly occurs after acquired brain impairment. It is characterised by impaired initiative, diminished activity, and lack of concern; formally delineated as a decrease in cognitive, behavioural and emotional components of goal-directed activity. The impact is widespread, hampering rehabilitation and outcome. This systematic review identifies and assesses the efficacy of non-pharmacological treatments for apathy following four types of acquired brain impairment (traumatic brain injury, dementia, cerebrovascular accident, encephalitis). Nine databases were searched. Studies were reviewed according to the following criteria: age over 16 years, acquired brain impairment, non-pharmacological intervention for apathy, and data reported on treatment efficacy. The methodological quality of the studies was assessed. Searches yielded 1754 articles, with 28 meeting criteria. Methodological quality ranged greatly. The majority of trials involved the dementia population. Cognitive interventions were the most frequent mode of treatment. For those with severe impairments, the strongest evidence suggested music therapy and for milder impairment, the strongest evidence was for cognitive rehabilitation. This review reveals a need for more high quality, methodologically rigorous treatment studies for apathy, particularly within the milder ranges of impairment. Initially, however, a uniform operational definition needs to be utilised in all research studies to minimise variability. Additionally, employing a standardised outcome measure specific to apathy would greatly enhance comparison among treatments.