Keeping up with the monolinguals: An equal pace of vocabulary development between Dutch monolingual and bilingual infants in the first 18 months after birth

Previous studies investigating possible differences between monolingual and bilingual infants’ vocabulary development have produced mixed results. The current study examines the size of the total receptive and expressive vocabulary, total conceptual vocabulary, and specific Dutch vocabulary of two hundred 8- to 18-month-old monolingual and bilingual infants born and living in the Netherlands. Families completed a Dutch version of the MacArthur-Bates Communicative Developmental Inventories. Results illustrate that bilingual infants keep up with monolinguals even in Dutch receptive and expressive vocabulary sizes, showing no trace of delay in the development of the socially dominant language. The overall findings constitute an extension of work on vocabulary acquisition and challenge existing theories that suggest a developmental delay among bilingual learners. The equal pace of development between the monolingual and bilingual groups provides new insights into the influence and perhaps advantages of early bilingual language acquisition.