Chapter 11: Child Language Acquisition

11.9 Growing up bilingual (or multilingual!)

There’s a bias in the literature on children’s language acquisition: a lot of it focuses on kids who are acquiring just one language, but monolingual kids are not the norm around the world. It is just as common for children to grow up with more than one language in the environment. Some children have one language in the home environment and another at daycare. In some families, one adult speaks one language and another adult speaks a different one. And some kids grow up in an environment where all the adults switch between two or three languages. In Canada and the US, where English has privileged status, it has been common for English-speakers to believe that being bilingual is a disadvantage, or even harmful! Bilingual kids were thought to be less intelligent and at greater risk for developmental delays and so-called “emotional disorders”. Even today in Canada it’s not unusual for a teacher or a doctor to advise parents who speak another language that they should speak English at home so their child doesn’t get confused. This is also the kind of thinking that leads hearing parents of deaf kids to worry that if their child learns a signed language, it’ll interfere with their acquisition of a spoken language. So is it risky for kids to be bilingual? Instead of opinions, let’s look at the evidence.

Remember that children’s mental grammars develop in response to input from the language environment: whatever language is used by the people around them, that’s the language that a child learns. The amount of language input plays a role in kids’ rate of acquisition. As we saw above, deaf children who don’t have access to language input in a vocal language environment can’t develop a mental grammar for that vocal language. And on a much smaller scale, an only child who is at home with one adult all day might not get a lot of language input and so might not show much language use until they start going to daycare where they get exposed to lots of language in the environment.

Let’s compare the language environments of two hypothetical children. To make this example simple, let’s say they’re each awake for twelve hours a day, and as long as they’re awake, they’re exposed to language input. The child in the monolingual environment gets twelve hours of Language A every day. The child in the bilingual environments gets, say, six hours of Language A and six hours of Language B: they just don’t get the same quantity of either language as the monolingual child does. So it takes a little longer for them to have encountered enough language to build up the mental grammar for each of their two (or more) systems. In other words, if you measure a bilingual child’s language development in one of their two languages, they might be a little delayed relative to a monolingual child’s development. Their vocabulary in the one language is a little smaller, and it takes them a little longer to reach the typical milestones in grammatical development (Hoff et al., 2011). But that’s only if you compare the one language! If you compare the size of a bilingual child’s vocabulary across both their languages, it’s the same or even bigger than that of a monolingual at the same age (Hoff et al., 2014). So it’s true that there’s sometimes a slight delay in bilingual kids’ development in each of their languages, relative to monolingual kids, when measured using the tests that are standardized for monolinguals.

But remember that language acquisition is not a race! Reaching a milestone a few weeks later than other kids needn’t be cause for concern. There is a lot of variation between children and between language environments. Some research indicates that the delay is within the normal range of variation for monolingual kids, and some suggests that most bilingual kids catch up to monolingual kids in both their languages by about age ten. In that case, why would there be pressure on parents who have immigrated to Canada to speak English at home? If you think back to previous chapters, it probably has more to do with power and privilege than with children’s development. The stigma associated with non-English languages and with so-called “foreign” accents also extends to children, which means that monolingual teachers and doctors sometimes perceive “problems” in bilingual kids that they don’t notice in monolinguals.

So the evidence shows us that bilingual kids might have some slight delays in their language development, but these delays aren’t harmful and the kids usually catch up with their monolingual peers eventually. The evidence also suggests that there are advantages to acquiring more than one language. A lot of research has looked at executive function, the set of mental processes that govern your attention and control your impulses. There is a body of evidence that suggests that bilinguals score higher than monolinguals on measures of executive function (Bialystok, 2009; Byers-Heinlein et al., 2017; Peal & Lambert, 1962). The idea is that, when you’re bilingual, your mind is always busy suppressing one language in order to process information in the other language, and this skill transfers to other areas where the mind needs to inhibit irrelevant information to focus on something. I should make it clear that there’s a lot of argument among psychologists and linguists about these effects, because there are so many different ways of defining “bilingualism” and because so many other factors besides language contribute to executive function, but it seems to be the case that being bilingual is one of the factors that can support executive function. If you’d like to learn more about this debate, you might be interested in reading Valian (2015) for a useful summary.

Besides the executive function research, there’s also evidence that acquiring more than one language shapes kids’ expectations about people. Well before age 1;0, children tend to expect other humans to be cooperative: they show surprise (evidenced by longer looking times) when an adult is trying to reach an object and another adult passes them something different (Vouloumanos et al., 2014). If the adults in this scenario speak an unfamiliar language, 14-month-old bilingual children are still surprised: it seems that they expected the adults’ speech to be communicating a message so they’re surprised at the lack of cooperation. But monolingual children react differently: if the adults speak a language that’s unfamiliar to the children, then the children don’t show surprise when the adult is uncooperative, which kind of suggests they didn’t expect that unfamiliar speech to be conveying any meaningful message (Colomer & Sebastian-Galles, 2020). There’s also recent evidence that bilingual toddlers and preschoolers show less racial bias than monolingual kids on tests of implicit bias and of spoken word recognition (Singh, Quinn, et al., 2020; Singh, Tan, et al., 2020).

For families who immigrate, one of the most important benefits to raising kids bilingually is retaining the connection to older relatives. Whether or not bilingualism leads to executive function benefits or slight delays in vocabulary size, it’s incredibly valuable for kids to be able to communicate and have a relationship with their grandparents. Overall, there’s no evidence that growing up bilingual or multilingual does harm, while there is evidence that it can be beneficial, and it results in you knowing more than one language, which is pretty neat! If you’re interested in knowing how to support families in maintaining children’s bilingualism, Jürgen Meisel’s (2019) book is useful for non-specialists.


Check your understanding


Bialystok, E. (2009). Bilingualism: The good, the bad, and the indifferent. Bilingualism: Language and Cognition, 12(01), 3.

Byers-Heinlein, K., Morin-Lessard, E., & Lew-Williams, C. (2017). Bilingual infants control their languages as they listen. Proceedings of the National Academy of Sciences, 114(34), 9032–9037.

Colomer, M., & Sebastian-Galles, N. (2020). Language background shapes third-party communication expectations in 14-month-old infants. Cognition, 202, 104292.

Hoff, E., Core, C., Place, S., Rumiche, R., Señor, M., & Parra, M. (2011). Dual language exposure and early bilingual development. Journal of Child Language, 39(1), 1–27.

Hoff, E., Rumiche, R., Burridge, A., Ribot, K. M., & Welsh, S. N. (2014). Expressive vocabulary development in children from bilingual and monolingual homes: A longitudinal study from two to four years. Early Childhood Research Quarterly, 29(4), 433–444.

Meisel, J. (2019). Bilingual Children: A Parents’ Guide (1st ed.). Cambridge University Press.

Peal, E., & Lambert, W. E. (1962). The relation of bilingualism to intelligence. Psychological Monographs: General and Applied, 76(27), 1–23.

Singh, L., Quinn, P. C., Qian, M., & Lee, K. (2020). Bilingualism is associated with less racial bias in preschool children. Developmental Psychology, 56(5), 888–896.

Singh, L., Tan, A. R. Y., Lee, K., & Quinn, P. C. (2020). Sensitivity to race in language comprehension in monolingual and bilingual infants. Journal of Experimental Child Psychology, 199, 104933.

Valian, V. (2015). Bilingualism and cognition. Bilingualism: Language and Cognition, 18(1), 3–24.


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Essentials of Linguistics, 2nd edition Copyright © 2022 by Catherine Anderson; Bronwyn Bjorkman; Derek Denis; Julianne Doner; Margaret Grant; Nathan Sanders; and Ai Taniguchi is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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