The worry is common, but the evidence tells a different story
Many parents who speak more than one language at home worry they are doing something wrong. The fear is understandable. Children in bilingual homes may say their first word a little later in one of their languages, or have a smaller vocabulary in each individual language compared to a child who speaks only one.
But when researchers look at the whole picture — total vocabulary across both languages, overall cognitive development, long-term outcomes — bilingual children develop typically. In fact, growing up with two languages may bring real benefits, including stronger mental flexibility and the ability to focus attention in a noisy room.
The problem is not the science. The problem is that most parents never hear it.
A team of researchers recruited 76 Polish parents living in Norway — a real-world bilingual situation where families face daily decisions about which language to use with their babies.
Parents were randomly assigned to one of two groups. One group (40 parents) attended workshops specifically designed to share what current research says about language and bilingual development. The other group (36 parents) did not attend any workshops.
Researchers measured each parent's beliefs at three points in time: before the workshops, immediately after, and again when their children were around 9 months old.
This kind of study design — a randomized controlled trial — is considered a gold standard in research. By randomly assigning families to groups, researchers can be more confident that any differences they find are due to the workshops themselves, not just pre-existing differences between families.
What changed — and what didn't
The results were encouraging. Parents who attended the workshops showed significantly more alignment between their beliefs and the scientific evidence — immediately after the sessions and still months later when their babies were around 9 months old.
The control group showed no such change. That matters, because it tells us the shift in the workshop group was not just parents naturally updating their views over time.
One of the more striking findings: the parents who had the most to gain actually gained the most. Parents whose beliefs were farthest from the scientific evidence at the start saw the biggest improvement. That is a good sign for an intervention — it suggests it is reaching the people who need it most.
The study also found that how engaged parents were during the workshops, their starting belief levels, and their level of education all played some role in how much their beliefs shifted. But prior parenting experience — whether or not a parent had raised children before — did not seem to matter.
Why beliefs matter in the first place
You might be wondering: why does it matter what parents believe, as long as they are speaking to their child?
Think of it this way. A parent who believes that speaking Polish at home will confuse their child may start switching to Norwegian out of anxiety — and as a result, the child hears less rich, natural language from the parent who speaks it most fluently. A parent who understands that both languages are valuable may speak more freely, read books in their native tongue, and create a richer language environment overall.
Beliefs shape behavior. Behavior shapes the language environment. The language environment shapes the child.
That chain is why researchers are interested in changing what parents think — not just what they do.
What we still do not know
This study is genuinely exciting, but it is important to be clear about what it does and does not show.
The study measured parental beliefs — not child language outcomes. We do not yet know whether the children of parents who attended these workshops will actually speak sooner, develop larger vocabularies, or show stronger bilingual skills. The researchers themselves flag this as the most important next question.
The study also followed a specific group: Polish families living in Norway, who were already motivated enough to enroll in a research study. Results may look different in other communities, languages, or socioeconomic contexts.
The sample size — 76 families — is relatively small. Larger studies will be needed to confirm these findings and understand who benefits most.
- This study was conducted with a single immigrant population (Polish families in Norway) and may not generalize to other bilingual communities.
- No child language outcomes were measured; only parent beliefs.
- The follow-up point was 9 months of age, which is still early in language development.
- Parents who enrolled in a research study may already be more engaged or motivated than the average parent.
What this means for your family right now
If you are raising a child in a bilingual or multilingual home, the core message from decades of research is this: you are not hurting your child by speaking your language. You may be helping them.
And if you ever feel uncertain — or if well-meaning relatives keep telling you to "just pick one" — know that the science is on your side. Workshops like the ones in this study may not be available everywhere, but pediatricians, speech-language pathologists, and reputable parenting resources can help you understand what the evidence actually says.
The best thing you can do for your bilingual child might start with what you believe is possible.
Would you feel more confident speaking your native language at home if you knew the science actually supported it?
Related Reading
- How bilingual children develop language skills
- When to talk to a pediatrician about language milestones
- Supporting early language development at home