The Bilingual Aphasia Test (BAT) is designed to be objective (so it can be administered by a lay native speaker of the language) and equivalent across languages (to allow for a comparison between the languages of a given patient as well as across patients from different institutions). It has been used not only with aphasia but also with any condition that results in language impairment (Alzheimer's, autism, cerebellar lesions, developmental language disorders, mild cognitive impairment, motor neuron disease, multiple sclerosis, Parkinson's, vascular dementia, etc.). It has also been used for research purposes on non-brain-damaged unilingual and bilingual populations. By means of its 32 tasks, it assesses comprehension and production of implicit linguistic competence and metalinguistic knowledge (which provide indications for apposite rehabilitation strategies). Versions of the BAT are available for free download at www.mcgill.ca/linguistics/research/bat/. (Contains 24 notes.)