Bilingual Children: Dispelling the Myths of Language Acquisition

In my practice, I often see children who are growing up in a bilingual environment. Parents of bilingual children often wonder if, and how, bilingualism affects the process of language acquisition. “My child is behind in his speech, could it be because he hears two languages?” parents often ask. To clarify the facts and dispel the myths about the effects of bilingualism on language acquisition, I will take a closer look at the research on this topic. In thinking about the path of a bilingual child’s language development, here are some things to consider:

Is Your Child a Simultaneous or Sequential Learner?

Depending on the age of language exposure and acquisition, bilingual children are described as either simultaneous or sequential learners. A simultaneous learner, usually raised bilingually from birth, has acquired two languages before the age of three. (2)(3) A sequential learner is introduced to the second language after the first language is well established (typically after the age of three). A child that exclusively hears and speaks her native language at home, until entering school when instruction is offered in a different language, is a sequential learner. (2) Recognizing if your child is either a simultaneous or sequential learner is important, as each pattern results in a slightly different progression of language development.

Simultaneous Learners:

Simultaneous learners generally progress through two stages of language development. During the first stage, the child’s speech is “undifferentiated,” meaning the child mixes elements of both languages within a single sentence, and even uses word stems from one language with prefixes and suffixes from another language. This stage typically lasts until about three years of age.

During the second “differentiated system stage,” the child is able to distinguish between the two languages, identifying each system’s distinct uses and applications. After the child is able to associate one language with a specific person or situation, he develops the ability to alternate language use between contexts.

For simultaneous learners, early communicative milestones occur at ages similar to monolingual infants. (See table 1.) Thus, learning two languages at a young age should not cause a language delay. If a true delay exists, it will be present in both languages. Delays and severity noted will be similar to monolingual children with a language delay or disorder. (2)(3)

Table 1: Communicative Milestones for Simultaneous Learners

Age Stage Milestone Potential Red Flag
Birth–2 months Undifferentiated Cooing
2–6 months Undifferentiated Babbling No babbling sounds
6–15 months Undifferentiated First words appear (may be comparatively later than monolingual speakers, but still within range) Less than one new word per week
1–2 years Undifferentiated Language blend Produces less than 20 words in either language or combined, by 20 months
2–3 years Undifferentiated Language mixing Child has only produced a countable number of words by 30 months, and no word combinations
4 years + Differentiated Use of each language as a separate system

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Sequential Learners:

The process for a sequential learner is slightly different. These children tend to progress through a series of four stages. In the first stage, the child continues to use the first language in the second-language situation. When the child realizes that her native language does not work in this situation, she may enter what’s called a non-verbal period. During this stage, the child might appear nonverbal, as she gathers information about the new language and its uses. In the third stage, the child begins speaking publicly, using individual words and phrases in the new language. In the final stage, the child is able to productively use the second language in the appropriate context.(5) Milestones and potential warning signs depend on the particular stage your child is currently in.(2) (See table 2.)

Table 2: Communicative Milestones for Sequential Learners

Stage Milestone Red Flag
First language Normal language acquisition Milestones abnormal
Second language
Interactional period Use of expressive communication and fixed phrases Echolalia (the repetition of overheard words or phrases)
Inference period Grammatical rules of L1 are applied to L2 Syntactic error in L1
Silent period Selective mutism (length depends on temperament of child, may be longer in anxious children) Prolonged, or true mutism
Code-switching Switches between languages in the same conversation Word retrieval difficulties

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If your child is a sequential language learner, please note that this non-verbal period is common and should not immediately be interpreted as a problem in language acquisition. However, if your child remains in this non-verbal phase for more than seven months, or if your child demonstrates delays in the first language, talk to your pediatrician about your concerns.(5) Other professionals, such as Early Intervention providers (if your child is under three years of age), a speech and language pathologist, or a clinical psychologist with expertise in early childhood, are also qualified to address those concerns.

Receptive and Expressive Language

All language can be characterized as either receptive or expressive. Receptive language refers to the ability to comprehend language input. This includes understanding words, gestures, and phrases. Expressive language is the “output” of language, referring to the ability to communicate with others using language.(4)

Children typically develop receptive language skills earlier, as it is easier for children to absorb the sounds and rules of a language before they learn to express themselves verbally. Similar to monolingual children, bilingual children are often able to understand language before they are able to produce it.(1) Therefore, if you notice that your child’s expressive language appears to be developing slower than his receptive language, he may just need a little extra time. However, if you notice your child’s receptive language to be lagging as well, or if you are concerned that your child does not seem to understand words or phrases in either language, discuss your concerns with your pediatrician or another qualified professional.

If you are worried about your bilingual child’s speech and language development, I encourage you to seek out professional advice. Rather than waiting for the problem to resolve on its own or to become more pronounced, talk to your pediatrician or another qualified professional to see if an evaluation is warranted. In the meantime, you can continue to support your bilingual child by using gestures, speaking slowly, using short and simple sentences, and repeating, repeating, repeating!


  1. Dale, P. & Patterson, J., (2009). Early Identitification of Language Delay. In Encyclopedia on Early Childhood Development. Retrieved from
  2. Fierro-Cobas, V., & Chan, E. (July 2001). Language development in bilingual children: A primer for pediatricians. Contemporary Pediatrics, 18. Retrieved from
  3. Genesee, F. H. (2009). Early childhood bilingualism: Perils and possibilities. Journal of Applied Research on Learning, 2 (Special Issue), Article 2, pp. 1-21.
  4. Olson, G. (2012, May 15). Expressive vs. Receptive Language. [Web log post]. Retrieved from
  5. Staniforth, L. (2012). Child Language Development in Bilingual or Multilingual Environments [Powerpoint slides]. Retrieved from
  6. Tabors, P. (1997) One Child, Two Languages: A Guide for Preschool Educators of Children Learning English as a Second Language. Baltimore: Paul Brookes Publishing


This article was prepared with the invaluable help of Lindsay Rosen, a second year graduate student at Tufts University’s Eliot-­Pearson Department of Child Study and Human Development. Lindsay is passionate about understanding and improving the lives of individuals affected by various neurodevelopmental and psychological issues. Her ultimate goal is to work as a clinical psychologist and assist families through evaluation and treatment. Lindsay is currently interning at Growing Minds, LLC, where she helps Dr. Dashevsky gather research-­based literature on topics or clinical issues that arise in the course of Dr. Dashevsky’s work with children and families.