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The importance of language input – the evidence

This article describes the research that shows the importance of both quantity and quality of language input in language development.
Adult holding up a card with a 5 on it

Language input is “the totality of language [that children] hear”1.

Both the quantity and the quality of language input are important for language development2 and vary hugely between families, whether monolingual or multilingual.

Quantity of language input


The age at which input in different languages begins influences language development1. There are differences in language development between children who receive input in more than one language from birth, compared with those who are monolingual initially and receive language input in a second language later on in childhood – when they start attending school for example. Preschool multilingual children who are exposed to two languages sequentially understand fewer words in their second language compared with those who receive input in both languages from birth (simultaneously)3,4.

Time and amount

Longer exposure to a language is associated with better language outcomes in the same language, at least in the preschool years, and greater exposure to a second language was associated with more accurate tense inflection in English (for example, the use of -ed for past tense) in sequential multilinguals5.

Quality of language models

Lexical diversity

In a sample of 25-month-old Spanish-English bilingual children, the proportion of English input from native English speakers predicted English vocabulary and grammar acquisition6. This finding was subsequently replicated in a sample of 30 month old children7. Greater lexical diversity in language input from parents/caregivers at 18 months has been found to predict child vocabulary at 24 months in multilingual children8. These findings have important implications as they indicate that language input from native speakers is more beneficial for children’s language development than input from non-native speakers. In other words, parents can be encouraged to speak to their children in the language they are most proficient in, as this will result in better language development than speaking to them in a language they’re less proficient in.

Number of different speakers

There is also some evidence that the number of different speakers of a language that a child is exposed to can have an impact on language development. The number of native speakers of English as a source of input was associated with better language outcomes in English6 but not in Spanish in a sample of young bilingual children. This effect was also found in Spanish but not English is a slightly older sample7. Older siblings also play an important role: children with older siblings who speak the societal language have increased vocabulary in that language and, conversely, the absence of older siblings has been found to be associated with increased vocabulary in the child’s heritage language9.


Educating parents of multilingual children on the importance of language input is crucial. What kinds of resources and activities have you found to be effective? Please share details and ideas with fellow learners.

Optional activity

If this is a key challenge in your professional practice, why not take the time to collect together some of these resources and ideas and create an infographic or leaflet that could be used as part of a training activity for parents and carers.


  1. De Hower, A. (2018) The role of language input environments for language outcomes and language acquisition in young bilingual children: The role of language input environments for language outcomes and language acquisition in young bilingual children in Miller, D., Bayram, F., Rothman, J., Serratrice, L. Bilingual Cognition and Language: The State of the Science Across Its Subfields, p129.
  2. Anderson NJ, Graham SA, Prime H, Jenkins JM, Madigan S. Linking Quality and Quantity of Parental Linguistic Input to Child Language Skills: A Meta-Analysis. Child Dev. 2021 Mar;92(2):484-501. doi: 10.1111/cdev.13508
  3. Bialystok E, Luk G, Peets KF, Yang S. Receptive vocabulary differences in monolingual and bilingual children. Biling (Camb Engl). 2010 Oct;13(4):525-531. doi: 10.1017/S136672890999042
  4. De Houwer, A. (2010) Assessing lexical development in Bilingual First Language Acquisition: What can we learn from monolingual norms? In M. Cruz-Ferreira (Ed.), Multilingual norms (pp. 279– 322). Frankfurt: Peter Lang
  5. Blom, E., & Paradis, J. (2015). Sources of individual differences in the acquisition of tense inflection by English second language learners with and without specific language impairment. Applied Psycholinguistics, 36(4), 953-976. doi:10.1017/S014271641300057X
  6. Place, S., & Hoff, E. (2011) REFERENCE NEEDED
  7. Place, S., & Hoff, E. (2016). Effects and noneffects of input in bilingual environments on dual language skills in 2 ½-year-olds. Bilingualism: Language and Cognition, 19(5), 1023-1041. doi:10.1017/S1366728915000322
  8. Gámez PB, Palermo F, Perry JS, Galindo M. Spanish-English bilingual toddlers’ vocabulary skills: The role of caregiver language input and warmth. Dev Sci. 2022 Aug 1:e13308.
  9. Bridges K, Hoff E. Older Sibling Influences on the Language Environment and Language Development of Toddlers in Bilingual Homes. Appl Psycholinguist. 2014 Mar;35(2):225-241. doi: 10.1017/S0142716412000379
© University of Reading
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Understanding Multilingual Children's Language Development

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