Purpose: Given that children with Down syndrome (DS) have language learning difficulties, concerns have been raised about the capacity of these children to acquire two (or more) languages. This research examines the language profiles of bilingual children with DS and typically developing (TD) children in comparison to monolinguals, with a view towards identifying the factors associated with language abilities within these populations.

Method: Four groups of children were recruited: Welsh-English bilinguals with DS (n=10), English monolinguals with DS (n=10), TD Welsh-English bilinguals (n=10) and TD English monolinguals (n=10). Children were individually matched on nonverbal cognitive ability (NVCA) to each child in the bilingual DS group and the four groups were matched on socioeconomic status and gender. Bilinguals were matched on current and lifetime exposure to Welsh and age of first exposure to their L2. Within DS and TD groups, chronological age was statistically controlled for. Language abilities were assessed via standardised assessments and specially designed tasks. Bilinguals were assessed in both of their languages.

Results: Results show no effect of language status on measures of expressive and receptive language abilities or phonological awareness. Language impairments were evident for both DS groups, particularly for expressive morphosyntax. Welsh receptive vocabulary scores of the bilinguals with DS were comparable to the TD bilinguals. Working memory, phonological awareness and chronological age were the strongest predictors of receptive language outcomes in both DS groups, explaining 90% of the variability.

Conclusions: In conclusion, we report no adverse outcomes on language development for bilinguals with DS. To our knowledge, this is the first group study of bilingualism in children with DS within the UK. Findings align with and add to the growing body of literature that reports that bilingualism does not negatively impact the language development of children with developmental disabilities. Clinical and educational implications are discussed.