NO!
Bilingual children’s language development does not lag behind that of their monolingual peers. In fact, bilingualism has many positive effects on language acquisition and development.
Bilingual children might appear to have a more limited vocabulary than monolingual peers. In reality they usually speak the same number of words, spread across their two languages.
For example, a monolingual 18-month old typically says about 50 words. A bilingual 18-month old might say 20 words in one language and 30 in another. Their vocabulary development falls within the normal range, but it might seem like they are speaking less than their monolingual peers because their vocabulary is spread across two languages.
This chart shows that the combined vocabulary for average bilingual 2-year-olds is the same as their monolingual peers:
Bilingualism neither increases nor decreases the likelihood of language delays or learning difficulties, and it is rarely, if ever, the cause. However, learning difficulties can occur within bilingual children just as with monolingual children; if you’re concerned about speech delays you should always consult your pediatrician.
Bilingual children who acquire two languages early in life will almost always grow up to communicate as effectively in two languages as they would in one.
For more information, see “A Parents’ and Teachers’ Guide to Bilingualism by Colin Baker”
