According to the AAP, "more than 20% of children in the United States use a language besides spoken English at home."[1] If your family is one of them, you may wonder whether two languages could slow your child's talking, confuse them, or hide a real speech or language problem. The AAP and ASHA note that common myths about multilingualism "can lead families to restrict their child's exposure to their heritage languages."[1] This post summarizes what the American Academy of Pediatrics (AAP), the American Speech-Language-Hearing Association (ASHA), published research, and federal special education rules say about children learning more than one language.
Does learning two languages cause a speech or language delay?
In a parent guide published jointly by the AAP and ASHA, the answer to this question is a direct "No." The guide explains that early communication milestones "such as giggling, smiling and babbling, are the same in all languages," and that first words around 12 months and two-word phrases by 24 months "are the same developmental milestones for children no matter how many languages they are exposed to."[1]
The same guide states that "speech or language problems are not caused by learning multiple languages," and notes that "it is common for children all over the world to learn multiple languages without any difficulties."[1] A review by researchers Erika Hoff and Cynthia Core describes how an older view, that hearing two languages "caused confusion and impaired children's ability to learn either language," came from "methodologically inadequate research" and "is no longer taken seriously among researchers."[2]
Why does my bilingual child seem to know fewer words?
This is one of the most common worries, and the research gives a helpful explanation. Hoff and Core write that children learning two languages "build linguistic knowledge at a rate comparable to or greater than is observed in children who hear and acquire only one language." But because that growth is divided between two languages, young bilingual children "tend to lag behind monolingual children of the same age in vocabulary and grammatical development when measured in each language separately."[2]
The AAP and ASHA guide gives a simple example: a child who speaks only English "may have 50 words in English by age 2 years," while a child learning English and Spanish "may have 25 words in English and 25 words in Spanish. They both have the same total number of words."[1] Children also tend to learn different words in each language. Hoff and Core note that a child may know "words for school-related items in English and for home-related items in their heritage language."[2]
Hoff and Core are also honest that it "will likely take longer for bilingual children to acquire each language, and this is perfectly normal."[2] So the useful question is usually what your child can say and understand across all their languages together, not in English alone.
Is it a problem when my child mixes languages?
Hearing a sentence like "quiero mas juice" can make parents wonder if their child is mixed up. According to the AAP and ASHA, "this is normal. It does not mean that your child is confused." The guide adds that "usually by age 3, multilingual children can separate their languages," using the language that fits the person they're talking with.[1] Hoff and Core similarly report that research makes clear "young bilingual children distinguish between their two languages in their own use."[2]
The research on how parents mix languages is more mixed. Hoff and Core describe one finding linking parents' mixing of words from both languages within the same sentence to smaller comprehension vocabularies at 18 months, while other studies found no such relationship. They conclude that "it is possible that language separation is not necessary for children to learn two languages."[2] In other words, the evidence here is limited, and there's no single rule every family needs to follow.
Should we stop speaking our home language so our child learns English?
The AAP and ASHA guide answers this one with a clear "No," too. It advises that "parents and caregivers should use the language(s) they're most comfortable with when communicating with their child," and tells parents: "You will not confuse your child, set them back academically, or prevent them from learning English by using your language(s) with your child."[1]
Hoff and Core reach a similar conclusion, writing that parents "do not necessarily benefit their children by avoiding use of the heritage language and speaking only English," and may be "diminishing their children's opportunities to acquire the heritage language without comparable benefit to the acquisition of English."[2] The AAP and ASHA guide also suggests reading books in your heritage language to build vocabulary.[1] Our post on supporting speech and language at home has everyday ideas that work in any language.
From the AAP and ASHA: "If a child has a speech or language problem, it will show up in all languages that a child uses."[1]
How can I tell a language difference from a language disorder?
That callout is the key idea. Being behind in English alone, especially for a child who mostly hears another language at home, is expected. A true speech or language disorder isn't limited to one language.[1] The general milestones and warning signs that pediatricians use still apply to bilingual children. The AAP encourages parents to tell their child's doctor if development seems delayed, or "if your baby stops talking or doing things that he or she used to do."[3] It also advises: "It's important to have your child evaluated if you are concerned about your child's language development."[3]
Testing a bilingual child takes care. Hoff and Core explain that using tests designed for single-language children on just one of a bilingual child's languages "results in an underestimate of bilingual children's overall language knowledge, and over-identifies children at risk." They describe a common recommendation that speech-language pathologists "test in both of a child's languages," and suggest that decisions also draw on "parent and clinician impression, family history of language impairment, delays in comprehension, and use of communicative gestures."[2] Your observations about how your child communicates at home, in every language, are an important part of the picture. You can read more about what goes into a speech and language evaluation.
What do schools have to do when evaluating a bilingual child?
Federal special education regulations under the Individuals with Disabilities Education Act (IDEA) speak to this directly. Assessments must be "selected and administered so as not to be discriminatory on a racial or cultural basis," and must be "provided and administered in the child's native language or other mode of communication and in the form most likely to yield accurate information on what the child knows and can do academically, developmentally, and functionally, unless it is clearly not feasible to so provide or administer."[4]
The rules also state that a child must not be found eligible for special education if the determinant factor is "limited English proficiency."[5] So learning English, on its own, isn't a disability. If you have questions about how your child was evaluated at school, it's reasonable to ask which languages were tested. Our post on why some kids don't qualify for school speech services covers more about school eligibility.
Can a child with a speech or language disorder still learn two languages?
Yes, according to the AAP and ASHA guide: "Research shows that children with speech, language and other developmental disorders can learn additional languages," with plenty of exposure and practice. The guide says parents "should not hesitate to use multiple languages around (and with!) their child who has a speech or language disorder."[1] It also notes that a speech-language pathologist can work with a child in their heritage language, either by speaking that language or by working with an interpreter, and suggests asking your child's speech-language pathologist about activities that support "communication skills in all their languages."[1]
For younger children, the AAP explains that a doctor may refer a child under 3 to an early intervention program, and that families can also contact the program themselves.[3] See our early intervention page for background.
The bottom line
According to the AAP, ASHA, and published research, learning two languages doesn't cause speech or language problems, mixing languages is a normal part of bilingual development, and keeping your home language is encouraged. Bilingual children may know fewer words in each language, but their total vocabulary across languages is what matters. If you notice concerns in all of your child's languages, or simply have a gut feeling something isn't right, talk with your pediatrician or a speech-language pathologist about an evaluation that looks at every language your child uses.
Sources
- American Academy of Pediatrics and American Speech-Language-Hearing Association (2024). Young Children Learning Multiple Languages: Parent FAQs. HealthyChildren.org.
- Hoff, E., & Core, C. (2013). Input and Language Development in Bilingually Developing Children. Seminars in Speech and Language, 34(4), 215-226.
- American Academy of Pediatrics (2019). Language Delays in Toddlers: Information for Parents. HealthyChildren.org.
- U.S. Department of Education (n.d.). 34 CFR § 300.304 - Evaluation procedures. Electronic Code of Federal Regulations.
- U.S. Department of Education (n.d.). 34 CFR § 300.306 - Determination of eligibility. Electronic Code of Federal Regulations.
Articles from Speech Me Therapy, a pediatric speech-language therapy practice in North Phoenix serving Scottsdale, Paradise Valley, and families across Arizona by telehealth. Our posts summarize published guidance from professional and public health organizations; sources are listed at the end of every article.