A bilingual baby does not talk later than another child. Research shows no language delay attributable to hearing two languages from birth. What changes is the distribution: vocabulary is divided between the two languages, and each takes time to become established.
One practical question remains, one that all families ask themselves: how much does a language need to be spoken for the child to speak it in turn? The data exist, and they are clearer than one might think.
Does a bilingual baby talk later?
No. First words appear within the same windows as those of a monolingual child, generally around twelve months, with considerable individual variability.
The idea of a delay stems from a measurement error. If you count a bilingual child's vocabulary in only one of their languages, they appear to be behind. If you add both together, the difference largely disappears.
The classic milestones for language development from 0 to 3 years therefore remain valid. They simply apply to all of the child's languages as a whole, not to just one.
What bilingualism really changes
It shifts the distribution of vocabulary, not its total amount.
In her synthesis published in September 2017 for the Encyclopedia on Early Childhood Development, researcher Ellen Bialystok observes that bilingual children's vocabulary is less developed in each language considered separately. She never describes this difference as a delay.
The reason is mechanical. A child has a finite number of waking hours. If they divide them between two languages, they hear each one less often than a child who hears only one. Vocabulary follows this exposure.
Practical consequence: a bilingual child may know the word “spoon” in one language but not the other, simply because meals take place in only one of the two.
How much exposure is needed for a language to take hold?
Much more than one might think. Occasional exposure is not enough to produce an active speaker.
What the Belgian study of 1,899 families shows
In 2007, Annick De Houwer studied the language practices of 1,899 Belgian families living in a bilingual context. For each parental configuration, she recorded the proportion of children who actually spoke the minority language.
- Both parents speak the minority language at home: 97 % the children speak it.
- One bilingual parent and one parent who speaks only the minority language: 93 %.
- Each parent speaks their own language: 73 %.
- One bilingual parent and one parent who speaks only the majority language: 34 %.
The contrast between the first and last lines is the most useful finding of this study. Transmission does not depend on a method, but on the actual amount of language heard at home.
“One person, one language” is not a magic rule
The “one person, one language” principle means that each parent always speaks to the child in their own language. It is often presented as the standard method.
The figures above add nuance: this arrangement produces 73% of children who speak both languages, significantly fewer than when the minority language is used throughout the home. It works, but it is not the most effective approach.
A Dutch study conducted by Sharon Unsworth in 2013 with 136 children measured weekly exposure rates ranging from 8% to 93% of the time. This variation explains a large part of the differences observed between families.
Why babies mix the two languages
Mixing is normal and temporary. It indicates neither confusion nor difficulty.
A two-year-old who inserts a word from one language into a sentence in the other is doing what bilingual adults do: using the word they have available. The phenomenon decreases as each vocabulary becomes more complete.
It also increases when the child knows that their conversation partner understands both languages. This is social adaptation, not a deficiency. This nuanced reading of situations ties in with what we describe regarding emotional intelligence between ages 0 and 3.
What bilingualism brings
A documented advantage in executive control, that is, the ability to inhibit one piece of information in order to focus on another.
Ellen Bialystok reports that bilingual children aged four to eight show a marked advantage in problem-solving tasks that require this attentional inhibition. The explanation is straightforward: speaking one language constantly requires keeping the other in the background.
This advantage does not make a bilingual child more intelligent. It relates to a specific function, and the reported effects vary from study to study. Caution is still warranted on this point.
When should you be concerned and seek advice?
When the delay affects both languages at the same time. A delay in only one language is almost always explained by exposure.
The warning signs are the same as for a monolingual child: no babbling by around nine months, no words by around eighteen months, no combination of two words by around age two, or loss of previously acquired skills. A doctor or speech-language therapist then assesses all of the child's languages, never just one.
Bilingualism should never be used as the default explanation for a delay. This is a common mistake that postpones identification.
What helps in everyday life
Three principles emerge from the available data, and they can be summed up in a few words.
Increase the amount, not the method. A language takes hold when it is heard often and for long periods. Books, songs, meals, journeys: repeated moments are what matter, as we explain in our article about talking to your child from birth.
Speak the language you are comfortable with. The quality of the relationship matters as much as the amount of exposure. A parent who speaks a language they do not master well impoverishes the interaction without any benefit.
Rely on play rather than screens. A language is acquired through interaction, not by watching a video: our article on screens before age 3 details the evidence on this point. Pretend play between 18 and 36 months, meanwhile, is an excellent outlet for expression.
Two practical levers also help. Baby sign language can serve as a bridge before the first words. Childcare, meanwhile, mechanically determines the share of the majority language in the week.
Finally, the environment matters. An accessible play and reading area, with books in both languages within the child's reach, creates more opportunities for interaction than a neatly arranged bookshelf out of reach.
In summary
Early bilingualism does not delay language development. It distributes vocabulary across two languages, and the minority language survives only if it has a real place in daily life. The rest comes down to time spent together.
Have more questions about your child's development? Our FAQ brings together the most frequently asked questions and answers.
Sources
- Bialystok, E., “Second-language acquisition, bilingualism during early childhood, and their impact on early cognitive development,” Encyclopedia on Early Childhood Development, 2nd revised edition, September 2017.
- De Houwer, A., “Parental language input patterns and children's bilingual use,” Applied Psycholinguistics, 2007 — a survey of 1,899 Belgian families.
- Unsworth, S., “Assessing the role of current and cumulative exposure in simultaneous bilingual acquisition,” Bilingualism: Language and Cognition, 2013 — 136 children.
This article is for informational purposes and does not replace the advice of a healthcare professional. If you have any concerns about your child's language development, talk to your doctor.
