AbstractBackgroundThe Cognitive Domains and Functional Assessment Questionnaire (QACDF) assesses cognitive and functional decline based on the DSM‐5 criteria for Neurocognitive Disorders¹. The QACDF has two versions, one for the patient and another for the informant. It is composed of 30 items, each assessed by a likert scale. This questionnaire has appropriate semantic characteristics for the Brazilian older adult population.MethodThe objective of this study was to translate, adapt and assess the semantic, idiomatic, experiential and conceptual equivalence of the QACDF. Firstly, the QADCF original version in Portuguese was translated to English by two Bilingual translators, a non‐specialist linguist and a specialist in the field. After this, the two translators (T1 and T2) together with a mediator translator synthesized the translations in a common version (T3). Then, the T3 version was back‐translated into Portuguese by a Bilingual translator, blind to the original version². The three versions (original, translated and back‐translated) were assessed by a committee of specialists. The committee was composed of the initial translators, an English native speaker, an expert in the methodology and the main researchers.ResultThe QACDF Items were adjusted to conceive equivalent expressions for the target language, as well as to assess cognitive domains and the functionality of daily living of English speakers. Semantic, idiomatic, experiential and conceptual equivalence were debated by the committee until consensus was reached.ConclusionThe translation of the instrument followed the proposed methodology by Beaton et col. However, while the Brazilian Portuguese versions have been assessed by two pilot studies, pilot studies are still needed to further adjust the questionnaires for English speakers.