Nearly half the people in the world speak two languages, yet many myths persist regarding bilingual language development (Grosjean, 2010). Although a bilingual child’s language development may not follow the exact same trajectory as a monolingual speaker’s, the differences do not result in any speech or language delay or disorder. In fact, a large body of research has proven that bilinguals meet many language milestones at the same age as monolinguals (e.g., Oller, Eilers, Urbano, & Cobo-Lewis, 1997; Pearson, Fernandez, & Oller, 1993; Petitto et al, 2001).

There are two ways in which children learn more than one language. The first one is called simultaneous acquisition, which is when a child is introduced to more than one language from birth or before age three. When children learn more than one language, they experience the same developmental stages that a monolingual speaker would. They acquire two separate language systems at the same time, and can even differentiate the two languages which is illustrated by their ability to determine which language to speak to a particular speaker (e.g., speaking Spanish to a Spanish-speaking father, and speaking English to an English-speaking mother).

Another way children acquire language is through sequential acquisition, which is when a second language is introduced after the first language has been established, typically after age three. A child learning a new language after only having experience with a primary language may experience a silent period. A silent period can last from a few weeks to several months. During this time, they are listening and building their vocabulary and knowledge of the new language. This should not be a cause for concern, but if it lasts longer than several months it is best to contact a speech-language pathologist for an evaluation.

When bilingual children talk, they sometimes mix up words in the languages they know (e.g. a French and English speaking child saying, “Je veux nager à la swimming pool”). This is called “code-switching” and is a normal part of bilingual development, even being considered a sign of bilingual proficiency by researchers.

There are many ways parents can help their child learn more than one language, and it is a personal choice on how you choose to do it. Research shows that regardless of a parent’s approach (e.g., each parent speaking only one language, both parents mixing languages, etc.), a child will learn the languages and also mix them. Parents should choose whichever way they feel most comfortable speaking to their child.

Speech-language pathologists only determine there is a language delay or disorder if a deficit is present in both languages. If you think your child has a language delay, consult with a speech-language pathologist for advice.


Grosjean, François. Bilingual. Harvard University Press, 2010.

Oller, D. K., Eilers, R. E., Urbano, R., & Cobo-Lewis, A. B. (1997). Development of precursors to speech in infants exposed to two languages. Journal of Child Language, 24, 407–425. doi:10.1017/S0305000997003097

Paradis, J., Genesee, F., & Crago, M. (2011). Dual Language Development and Disorders: A handbook on bilingualism & second language learning. Baltimore, MD: Paul H. Brookes Publishing.

Pearson, B. Z., Fernandez, S. C., & Oller, D. K. (1993). Lexical development in bilingual infants and toddlers: Comparison to monolingual norms. Language Learning, 43, 93–120. doi:10.1111/j.1467-1770.1993. tb00174.x

Pearson, B.Z., Fernandez, S.C., Lewedeg, V., & Oller, D.K. (1997). The relation of input factors to lexical learning by bilingual infants. Applied Psycholinguistics, 18, 41-58.

Petitto, L. A., Berens, M. S., Kovelman, I., Dubins, M. H., Jasinska, K., & Shalinsky, M. (2012). The “perceptual wedge hypothesis” as the basis for bilingual babies’ phonetic processing advantage: New insights from fNIRS brain imaging. Brain and L