Study title

The data in this repository were collected in France, the Netherlands and the UK between 2020 and 2022 to inform the validation of the Q-BEx questionnaire (). Children between the ages of 5 and 9 were tested individually to assess their proficiency in the societal language (i.e., French, Dutch or English), as well as their non-verbal intelligence and working memory. One of their parents or caregivers also filled in the full version of the Q-BEx questionnaire. The respository includes data from 299 children (FR: n=78, NL: n=117, UK: n=104), although some measures are not available for all children. In France, children were recruited in ordinary schools and in private clinics for Speech & Language Therapy (37 children were recruited via clinics). The consent form for schools asked parents if the child had previous or current SLT, and the reason. In the Netherlands, recruitment took place in schools and via social media advertisement. Language disorder (reported by parent/teacher/remedial teacher) was an exclusionary criterion. In the UK, all children were recruited in schools; no exclusionary criteria were applied, and not SLT information was collected. Language experience data Language experience data was collected using the full version of the Q-BEx questionnaire (), which was completed by one of the child’s parents or caregivers. This includes all the following modules (except that Language mixing wasn’t included in France): - Background (languages the child is exposed to, adults and children the child lives with - Risk factors (early language milestones, early parental concerns) - Language exposure and use (current and cumulative estimates; onset of exposure to each language) - Estimates of proficiency in each language (listening, speaking, reading, writing) - Richness of experience in each language (activities, diversity of interlocutors, parental education) - Language mixing - Attitudes The questionnaire was administered either in the societal language...