Late Talkers

Does Bilingualism Cause Speech Delays?

January 24, 2023

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bilingual toddler and dad


Bilingualism refers to the ability to use two languages in everyday life and Bilingualism is common in many parts of the world

Several studies have even suggested that bilinguals show certain advantages! Bilingual people appear to perform a little bit better than monolinguals on tasks that involve switching between activities and inhibiting previously learned responses (Bialystok, Craik, & Luk, 2012).

Dad and bilingual toddler

But Can Bilingualism Cause Speech Delays?

Bilingual children often  mix words from two languages in the same sentence.  While parents may mistake this behavior is getting confused, this is known as code mixing and is a normal part of bilingual development

Bilingual children are not more likely than monolingual children to have difficulties with language, to show delays in learning, or to be diagnosed with a language disorder.

In their article, Bilingualism in the Early Years: What the Science Says, Krista Byers-Heinlein and Casey Lew-Williams do a wonderful job explaining this misconception:

“What we know is that while bilingual children typically know fewer words in each of their languages than do monolingual learners of those languages, this apparent difference disappears when you calculate bilingual children’s “conceptual vocabulary” across both languages (Marchman et al., 2010).  That is, if you add together known words in each language, and then make sure you don’t double-count cross-language synonyms (e.g., dog and perro), then bilingual children know approximately the same number of words as monolingual children (Pearson, Fernández, & Oller, 1993; Pearson & Fernández, 1994).”

The authors give an example: “If a Spanish/English bilingual toddler knows 50 Spanish words and 50 English words, she will probably not appear to be as good at communicating when compared to her monolingual cousin who knows 90 English words. However, assuming 10 of the toddler’s Spanish words are also known in English, then the toddler has a conceptual vocabulary of 90 words, which matches that of her cousin. “


Just like some monolingual children have a language delay or disorder, a similar portion of bilinguals will have a language delay or disorder and there is no evidence that bilingualism itself causes speech delays.

How to Foster Language Development:

Children learn through responsive interactions in their natural environment.  When parents interact in a responsive way during everyday activities by modeling language and being responsive, it helps children build their language skills regardless of what language is being used,

If you’re looking ways to support your little one’s language at home, check out my Free Late-Talker Guide or my online course for parents of late-talkers.


Bialystok, E., Craik, F. I. M., & Luk, G. (2012). Bilingualism: consequences for mind and brain. Trends in Cognitive Sciences, 16(4), 240– doi:10.1016/j.tics.2012.03.001

Heinlein, K, and Lew-Williams, C. Bilingualism in the Early Years: What the Science Says, LEARNing Landscapes | Vol. 7, No. 1, Autumn 2013, 95-112.

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