A child learning language isn't just learning words — they're building concepts. And in a bilingual or multilingual child, those concepts don't sit neatly inside one language. A toddler might understand "under" from hiding under the kitchen table while Mum speaks Vietnamese, and meet the English word "under" two years later during circle time at kindy. Same concept, different language label, different moment in time.
Understanding how this works changes everything about what we target in therapy, how we measure progress, and how we read a child's overall knowledge. This article is about the how and why; the companion article covers the practical strategies families and therapists can use at home and in sessions.
How Do Concepts Develop Across Multiple Languages?
A concept is an idea or category — like "dog," "big," "under," or "happy." A bilingual or multilingual child may learn the concept of "dog" in their home language first (because that's where they interact with the family pet) and learn the concept of "addition" in English first (because that's the language of their maths class).
Kohnert (2013) describes this as the distributed nature of bilingual knowledge — and the same principle applies to children who are growing up with three or more languages. A multilingual child's conceptual knowledge is spread across all of their languages, shaped by the contexts in which each language is used. This is completely normal and expected — it simply reflects the fact that different languages are used in different parts of a child's life.
What this means in practice:
- A child might know kitchen vocabulary in Vietnamese, religious vocabulary in Arabic, and playground vocabulary in English
- They might understand the concept of "full" in all their languages but only have the word for it in one or two
- Abstract concepts like emotions might be stronger in the language used at home with caregivers, while academic concepts are stronger in English
This distribution is not a gap or a weakness. It's a natural feature of bilingual development. A child who seems "behind" in English often has a rich conceptual world in their home language that we can build on beautifully. Some of the bilingual children I've supported over the years have arrived looking quiet and uncertain in English, and the moment a parent tells me what they can do in their home language, a completely different child comes into focus.
Why Are Some Concepts Stronger in One Language?
The strength of a concept in each language is directly linked to input and experience. Children learn concepts through meaningful interactions — conversations, play, stories, daily routines — and whichever language those interactions happen in will be the language where that concept is strongest.
Paradis, Genesee, and Crago (2021) explain that this is why bilingual and multilingual children's vocabulary in each individual language often looks different from that of monolingual peers. It's not that they know less — it's that their knowledge is organised differently, distributed across two, three, or more systems rather than one.
Some factors that influence which concepts are stronger in which language:
- Who speaks each language. If one parent speaks Mandarin and the other speaks English, the child may develop certain concepts more strongly in one language depending on which parent is involved in which activities.
- Context of use. Home language is often used for daily routines, family events, cultural activities, and emotional conversations. English is often the language of school, structured learning, and peer interaction.
- Amount of input. The more a child hears and uses a language, the more concepts they'll develop in that language. When children start school, English input often increases significantly, and home language concepts may plateau or even seem to reduce for a time.
- Type of input. Rich, varied, interactive input (conversations, storytelling, explanations) builds concepts more effectively than passive input (background TV, overhearing conversations).
What Should Therapy Target?
This is where things get really interesting — and where understanding bilingual concept development makes a practical difference to therapy outcomes.
Concepts That Transfer Across Languages
Many concepts, once learned in one language, transfer to the other. Kohnert (2013) describes this as cross-linguistic transfer of conceptual knowledge. If a child understands what "under" means — the actual concept of something being beneath something else — they can learn the word for it in their second language relatively quickly, because the concept is already in place.
This is powerful for therapy. It means that:
- If a child learns a concept in their home language, that understanding doesn't have to be rebuilt from scratch in English
- Targeting concepts in the child's stronger language can actually support their weaker language
- Therapy can be more efficient when it builds on what the child already knows, regardless of which language they know it in
Concepts that tend to transfer well include:
- Spatial concepts (in, on, under, behind, next to) — once a child understands that a ball can be under the table, they only need the new word, not the idea
- Size and quantity (big/little, more/less, full/empty) — these comparisons work the same way in every language
- Categories (animals, food, vehicles, clothing) — the grouping logic transfers even when the labels don't
- Actions (running, eating, sleeping, building) — verbs tied to everyday routines are usually understood across languages
- Emotions and states (happy, sad, tired, hungry) — feelings are universal, even when the words for them differ
Language-Specific Vocabulary
Some vocabulary items are more tied to a specific language or cultural context and don't transfer as easily. These include:
- Culturally specific words — foods, celebrations, family titles, or traditions that exist in one culture but not another
- Grammatical function words — articles, prepositions, and conjunctions work differently in every language and don't transfer directly
- Idioms and figurative language — these are unique to each language
- Phonologically similar words — the actual word labels need to be learned separately in each language, even when the concept is the same
In therapy, this means we need to be thoughtful about what we're targeting. If the goal is to build the child's understanding of a concept (like categories, sequencing, or following directions), we can work in either language and trust that the knowledge will transfer. If the goal is to teach specific English vocabulary for school, then English-specific work is needed — but it's most effective when it builds on concepts the child already has in their home language. This kind of cross-language work sits neatly alongside bridging therapy, which uses a child's stronger language as a scaffold for the newer one.
Why This Matters for Assessment Too
When assessing a bilingual or multilingual child's conceptual development, it's essential to look at every language they use. A child who can't name colours in English but can name them all in Arabic — or in Arabic and Somali — has the concept; they just need the English labels. That's a very different starting point from a child who doesn't understand the concept of colour in any of their languages.
This distinction changes the goals we set, the strategies we use, and the progress we expect. And it's why we always encourage families to share what their child knows and can do in their home language.
A question worth coming back to: when was your child's last hearing check? Concepts are built on the small words a child hears day in, day out — in every language they're learning. If those words are arriving muffled, it shows up across all of them.
Practical Takeaways for Parents
A few things that often help bilingual families:
- Keep using your home language. Every concept your child learns in any language is valuable and transferable. Rich home language input builds a strong conceptual foundation.
- Don't worry about overlap. It's fine if your child learns the same concept in both languages — having two labels for one concept strengthens it.
- Share what your child knows. If your child has a speech pathologist, telling them what your child can do in your home language helps shape better goals and builds on existing strengths.
Understanding how concepts develop across two languages helps us set meaningful goals, use effective strategies, and celebrate the full range of what your child knows. If you'd like to talk about how we can support your bilingual child's concept development, get in touch — we'd love to hear from you. Any actual clinical work — assessment, diagnosis, or therapy — happens through a proper consultation tailored to your child.
Ready for practical strategies? Read our companion article: Building Concepts Across Two Languages: Strategies for Brisbane Bilingual Families
Alexandra Bouwmeester is a Senior Speech Pathologist (MSPA, CPSP) with over 14 years' experience supporting bilingual and multilingual families. She offers mobile speech pathology to families across Brisbane's south side and Logan, bringing a deep respect for home languages to every session.
References
Kohnert, K. (2013). Language Disorders in Bilingual Children and Adults (2nd ed.). Plural Publishing.
Paradis, J., Genesee, F., & Crago, M. B. (2021). Dual Language Development and Disorders: A Handbook on Bilingualism and Second Language Learning (3rd ed.). Paul H. Brookes Publishing.
Verdon, S., McLeod, S., & Wong, S. (2015). Supporting culturally and linguistically diverse children with speech, language and communication needs. Journal of Communication Disorders, 58, 74–90.
