Candidates are provided a choice of taking the CACO in English or French. Having made that choice, candidates are provided with assessment materials only in the language of their choice and not in both languages.

For May/June only, the Waterloo administration is conducted in English only, while the Montréal administration is conducted in French and English.

Questions are written in French or in English. Once written, questions are translated as required and maintained in both languages within a question item "bank". The goal of translation is to ensure that both versions provide a comparable challenge to candidates, irrespective of the language in which the assessment is taken.

For candidates with uncertainty about the translation of specialized terminology, a copy of Le Nouveau Dictionnaire de la Vision by Michel Millodot, édition Médiacom Vision, 1997, may be useful in preparing for the CACO.