Raising a Bilingual Child: Will Two Languages Cause a Speech Delay?
If you are raising your child to speak more than one language, you have probably heard this concern from a well-meaning relative, neighbor, or even a doctor: "Won't learning two languages confuse them or slow them down?"
It is one of the most persistent myths in child development. Here is what the research actually shows.
The Short Answer: No
Bilingualism does not cause language disorders or delays. Attitudes against early bilingualism are often based on myths and misinterpretations rather than scientific findings. In fact, research demonstrates that children are born ready to learn the language or languages of their environments without confusion or delay.
Bilingual Children Meet the Same Milestones
One of the most common worries parents have is that their bilingual child seems to know fewer words than other kids their age. This concern usually comes from measuring only one language — which is not an accurate way to assess a bilingual child.
If a clinician screens children for language delay based on words known in only one language, a child who hears one language 30% of the time and another 70% of the time could be flagged incorrectly — even though their development is completely typical for their bilingual exposure pattern.
The right approach is to look at the full picture. Studies demonstrate that children with exposure to two languages do not have elevated levels of risk for developmental language disorder when compared to their monolingual peers.
What About Mixing Languages?
Many parents worry when their child mixes words from both languages in the same sentence — a behavior called code-switching or code-mixing. This is not a sign of confusion.
Using two languages in the same sentence is a natural form of communication used by many bilingual speakers, and mixing two languages is not bad. Research shows that as children grow and their linguistic abilities expand, they become increasingly able to distinguish between their two languages and adjust which one they use based on who they are talking to. Code-mixing is a normal — and even sophisticated — part of bilingual development.
Should I Stop Speaking My Home Language?
Some parents are told to drop their home language and speak only the majority language so their child catches up faster. Research is clear: this advice is not evidence-based, and it can actually do more harm than good.
Historically, professionals have recommended to bilingual families that they should only use one language when raising children with developmental disorders. However, such recommendations are not evidence-based and can decrease both the amount of high-quality speech infants hear and opportunities to practice conversational skills. Furthermore, the inability to communicate in a heritage language may exclude the child from family culture and values.
In fact, the opposite is true. Not using two languages can potentially result in language delays. Parents who try not to use their native language may make it harder for a child to learn any language well, since it may limit the quality and quantity of language exposure the child is receiving at home.
The bottom line: Speak to your child in the language that feels most natural and comfortable to you. The richness and warmth of your conversations matters far more than which language they are in.
The Real Benefits of Raising a Bilingual Child
Beyond being safe for language development, bilingualism carries real cognitive advantages. Bilingual children with specific language impairments, Down syndrome, and autism spectrum disorders are not more likely to experience additional delays or challenges compared to monolingual children with these same diagnoses. Bilingualism is not a risk factor — even for children who already face developmental challenges.
Research also points to broader cognitive benefits. Switching between languages strengthens the brain regions responsible for attention, problem-solving, and cognitive flexibility. Bilingual children understand language as a system earlier than monolingual children, leading to better reading and writing skills later.
When Should I Be Concerned?
While bilingualism itself is not a cause of delay, language delays can still occur in bilingual children — just as they can in any child. Just like some monolingual children have a language delay or disorder, a similar proportion of bilingual children will have one as well. Evidence that one bilingual child has a language difficulty is not evidence that bilingualism leads to language difficulties in general.
Here are signs worth discussing with a speech-language pathologist, regardless of how many languages your child is learning:
Fewer than 20 words total across both languages by 18–24 months
Not combining two words (e.g., "more milk," "daddy go") by age 2
Speech that is difficult to understand even by familiar people by age 3
Noticeable frustration when trying to communicate
No new words or language growth over several months
A Note for Families
To promote successful bilingual development, parents raising bilingual children should ensure that their children have ample opportunities to hear and speak both of their languages. Raising a child who speaks more than one language is not a risk — it is a gift, and one that research consistently supports.
If you have questions about your child's speech and language development, a qualified speech-language pathologist can help you understand what is typical for a bilingual child and whether any support is needed.
References
Byers-Heinlein, K., & Lew-Williams, C. (2013). Bilingualism in the early years: What the science says. Learning Landscapes, 7(1), 95–112. https://pmc.ncbi.nlm.nih.gov/articles/PMC6168212/
Hartman, C., & Rhemtulla, M. (2023). Exploring assumptions of the bilingual delay in children with and without developmental language disorder. Journal of Speech, Language, and Hearing Research. https://pubs.asha.org/doi/10.1044/2023_JSLHR-23-00117
Gonzalez-Barrero, A. M., & Byers-Heinlein, K. (2022). Bilingual language development in infancy: What can we do to support bilingual families? Psychonomic Bulletin & Review. https://pmc.ncbi.nlm.nih.gov/articles/PMC8866745/
Kohnert, K., Ebert, K. D., & Pham, G. T. (2021). Language disorders in bilingual children and adults (3rd ed.). Plural Publishing. (as cited in Raising Little Talkers)
Poulin-Dubois, D., Blaye, A., Coutya, J., & Bialystok, E. (2011). The effects of bilingualism on toddlers' executive functioning. Journal of Experimental Child Psychology, 108(3), 567–579.