3 Myths About Bilingual Children (Debunked by an SLP)
A speech therapist debunks the 3 biggest myths about raising bilingual children: confusion, speech delays, and vocabulary size. Evidence-based answers for worried parents.
Lindsey Carleton, MA, CCC-SLP | Bilingual Speech Language Pathologist with over 11 years of experience
3/2/20267 min read
3 Myths About Bilingual Children (Debunked by an SLP)
If you're raising a bilingual child, you've probably heard one of these myths from a well-meaning relative, friend, or even a professional. As a bilingual speech-language pathologist, I hear them weekly. Let's set the record straight with what the research actually shows.
Myths about bilingual children are remarkably persistent, even among healthcare professionals and educators. They cause unnecessary worry for parents and, worse, sometimes lead to harmful advice like dropping a heritage language. Every one of these myths has been thoroughly studied and debunked, but they continue to circulate because they sound plausible on the surface.
Let me walk you through the three biggest myths I encounter in my practice, explain why each one is wrong, and share what the evidence actually says.
Myth #1: Bilingual Children Get Confused by Two Languages
The Myth
"Learning two languages at once will confuse my child. They'll mix everything up and not learn either language properly."
The Evidence
Bilingual children are not confused. They demonstrate remarkable awareness of their two language systems from very early on.
This is probably the most widespread myth about bilingual children, and it has been debunked by decades of research. Studies show that infants as young as four months old can distinguish between two languages based on rhythm and intonation patterns. By the time they begin speaking, bilingual children already understand that they have two separate language systems.
The "evidence" people usually point to for this myth is language mixing, when a child uses words from both languages in the same sentence. But this is actually called code-switching, and it's the opposite of confusion. Code-switching is a sophisticated skill that follows grammatical rules from both languages simultaneously. The child is choosing the most efficient or expressive word from their combined vocabulary, exactly what bilingual adults do in conversation.
Research published in the Journal of Speech, Language, and Hearing Research shows that bilingual children who code-switch frequently actually demonstrate stronger metalinguistic awareness and cognitive flexibility. They understand language as a system better than many monolingual peers.
When a bilingual child says "Quiero the blue one," they're not confused. They're being brilliantly efficient, pulling the best word from two vocabularies in real time.
Furthermore, by age three to four, most bilingual children demonstrate clear language partner awareness, meaning they know which language to use with which person. They speak Spanish with abuela and English with their preschool teacher without being told to switch. That's not confusion. That's social intelligence.
Myth #2: Bilingualism Causes Speech Delays
The Myth
"My doctor said bilingualism might be causing my child's speech delay. We should focus on just one language."
The Evidence
Bilingualism does not cause, contribute to, or worsen speech and language delays. The rate of delays is identical in bilingual and monolingual populations.
This myth is not just wrong, it's potentially harmful. When families are told to drop their heritage language, children lose cultural connections, family communication pathways, and cognitive benefits, all based on misinformation.
Here are the facts. Approximately five to ten percent of all children experience speech and language delays, regardless of how many languages they're learning. This statistic holds true across monolingual, bilingual, and multilingual populations worldwide. Bilingual exposure does not increase the risk.
A 2023 study in the Journal of Speech, Language, and Hearing Research specifically examined assumptions about "bilingual delay" and found no evidence supporting the claim. Bilingual children reach the same developmental milestones (first words around 12 months, word combinations around 18 to 24 months) as their monolingual peers.
So why does this myth persist? Three main reasons.
First, assessment errors. When a bilingual child's vocabulary is measured in only one language, it will naturally appear smaller than a monolingual child's total vocabulary. But this is comparing apples to oranges. A bilingual child who knows 80 words in English and 60 in Spanish has a combined vocabulary of 140 words, which may be perfectly on track, even if 80 English words alone looks "behind."
Second, assessment tool bias. Most standardized speech and language tests were created for monolingual English-speaking children. Using these tools without bilingual norms or modifications can falsely flag bilingual children as delayed.
Third, clinician training gaps. Many pediatricians and even some speech-language pathologists receive limited training in bilingual development. Without understanding normal bilingual patterns (like the silent period, code-switching, or uneven vocabulary distribution), typical bilingual behavior can look like a red flag.
What to do if you receive this advice: If any professional recommends dropping a language, seek a second opinion from a bilingual SLP or one experienced with culturally and linguistically diverse populations. The American Speech-Language-Hearing Association (ASHA) is clear: continuing both languages is the recommended approach, even for children with diagnosed communication disorders.
Myth #3: Bilingual Children Will Have Smaller Vocabularies
The Myth
"Bilingual children know fewer words because their brain has to split its resources between two languages."
The Evidence
When measured correctly across both languages, bilingual children's total vocabulary is comparable to monolingual peers. Their conceptual vocabulary often exceeds monolingual norms.
This myth comes from a fundamental measurement error that unfortunately still appears in some clinical and educational settings. When you test a bilingual child's English vocabulary alone, it may indeed be smaller than a monolingual English speaker's vocabulary. This makes mathematical sense because the bilingual child divides their language input between two systems.
But here's what that single-language measurement misses. A bilingual child might know "dog" in English but "gato" (not "cat") in Spanish because they heard each word in different contexts. They might know food words primarily in Spanish (because that's the language used at mealtimes) and school words primarily in English. Each language captures different experiences and contexts.
When researchers measure conceptual vocabulary, the total number of unique concepts a child can name in any language, bilingual children consistently match and sometimes exceed monolingual norms. They don't have less language. They have language distributed across two systems, each reflecting different life contexts.
This example illustrates the point: the bilingual child appears "behind" if you only count English, but their total conceptual vocabulary is identical. And as they age and get more input in both languages, vocabulary grows rapidly in both systems.
Additionally, bilingual children develop what linguists call "translation equivalents," knowing the word for the same concept in both languages. Over time, this grows substantially, giving them vocabulary depth that monolingual children simply don't have.
Track Your Child's Development Across Both Languages
Our free Speech and Language Milestones Checklist is designed for bilingual families, with age-by-age benchmarks that account for combined vocabulary and typical bilingual patterns.
What the Research Actually Supports
Now that we've cleared away the myths, here's what the science consistently shows about bilingual children.
Bilingual children demonstrate enhanced executive function, including better attention control, task switching, and working memory. These cognitive advantages appear as early as age three and persist into adulthood.
Bilingual children show greater metalinguistic awareness, meaning they understand language as a system earlier than monolingual peers. This translates to advantages in reading readiness and literacy acquisition.
Bilingual children develop stronger perspective-taking abilities. Managing two language systems requires constant monitoring of the communication context, which builds social cognition.
Maintaining a heritage language strengthens family bonds, cultural identity, and self-esteem. Children who can communicate with grandparents, extended family, and community members in their heritage language show stronger emotional wellbeing.
How to Respond When You Hear These Myths
Whether it comes from a relative, a teacher, or a healthcare provider, knowing how to respond to bilingual myths protects your child and your family's language choices.
When someone says "They're confused," you might respond: "Actually, language mixing is called code-switching, and it's a sign of strong bilingual development. Research shows bilingual children distinguish their languages from as early as four months."
When someone suggests dropping a language, you could say: "Our SLP has confirmed that bilingualism doesn't cause speech delays. The American Speech-Language-Hearing Association recommends maintaining both languages, even during speech therapy."
When someone worries about vocabulary size, try: "We measure our child's vocabulary across both languages. When you count all the words they know in English and Spanish together, they're right on track for their age."
Frequently Asked Questions
My child seems to be behind in one language. Is that normal?
Yes. It is completely normal for bilingual children to be stronger in one language, and which language is dominant can shift over time based on input and social context. The dominant language is usually the one with more environmental exposure.
Can bilingual children with autism or other developmental differences still benefit from two languages?
Research increasingly shows that bilingual exposure does not negatively impact children with developmental differences, including autism, Down syndrome, and specific language impairment. These children benefit from the same cultural, social, and cognitive advantages of bilingualism.
My child's teacher is concerned about their English. Should we switch to English only at home?
No. Strengthening the home language actually supports English development. A strong foundation in any language transfers skills to the second language. Instead, talk with the teacher about bilingual development norms and how to support English growth alongside the home language.
How can I find an SLP who understands bilingual development?
Search ASHA's ProFind directory and filter for bilingual clinicians or those with experience in culturally and linguistically diverse populations. You can also ask potential SLPs whether they assess vocabulary across both languages and whether they have bilingual-specific assessment tools.
Keep Reading
How to Start Raising a Bilingual Child (Even If You're Not Fluent)
Bilingual Speech Development: What Every Parent Needs to Know
How to Teach Your Child Spanish at Home (5 Simple Strategies)
Confident Bilingual Parenting Starts Here
Palabra Garden's 12-month curriculum gives you evidence-based activities, vocabulary cards, and parent guides designed by a bilingual SLP. Give your child the gift of two languages with confidence.
About Palabra Garden
Palabra Garden is a Montessori-inspired bilingual curriculum for ages 2-5, created by a bilingual speech-language pathologist. Our 12-month program combines evidence-based speech therapy techniques with playful, hands-on learning in English and Spanish.
Author Bio
Hi, I’m Lindsey Carleton, MA, CCC-SLP, a bilingual speech-language pathologist with more than 11 years of experience and a fellow toddler mom. I created Palabra Garden to support families who want intentional, play-based learning at home.
Through my work as an SLP, I’ve seen how powerful early language, social-emotional development, and hands-on learning can be for toddlers and preschool-aged children. Palabra Garden brings those same principles into your home with bilingual activities, preschool curriculum ideas, and simple strategies that support growing minds.
I believe children learn best through connection, curiosity, and everyday moments of discovery.
