Does raising a child bilingual cause speech delay?

The short answer: two languages don't cause delay

This is one of the most common worries in bilingual families, and one of the most reassuring answers. The American Speech-Language-Hearing Association (ASHA) says children who learn more than one language develop language skills much as other children do. Using your languages with your child won't confuse them or slow their learning, and a strong base in one language supports learning another.

ASHA notes that most children learning more than one language say first words by about age 1 and use two-word phrases by about age 2, the same broad pattern as children learning one. See when babies start talking for the full timeline.

What's normal for bilingual toddlers

A few things are normal and worth knowing in advance, because they're often mistaken for a problem:

• Mixing languages in one sentence is normal. "I want more agua." It's part of learning and using two languages at once, not a sign of trouble.
• One language may lead, and which one leads can shift with the setting, the topic or the person.
• Vocabulary is split across languages. Your child may know "spoon" in one language and "cup" in the other. That's why counting only one language undercounts what they know.

Babies start out ready for this. Researchers at the University of Washington describe newborns as "citizens of the world," able to tell apart the speech sounds of every language. In the second half of the first year, they start to focus on the sounds of the languages around them. That narrowing is the brain getting efficient at the languages it actually hears.

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Count every word, in every language

If you're checking whether your toddler is on track, or a professional is checking for you, make sure words in every language count. "Agua" and "water" are both words.

The usual milestones then apply to the combined total. By 18 months, most children try to say three or more words besides "mama" or "dada." Speech specialists use a rule of thumb at 24 months: fewer than 50 words and no two-word combinations is a reason to check. For bilingual children, that means 50 words across all their languages, not in each one.

Here's how that works in practice. Say your 2-year-old has 28 words in Spanish and 25 in English, including pairs like agua and water. Both words in each pair count, so that's 53 words. Keep the list in two columns, one per language, and bring it to the checkup so nobody counts only half of what your child knows.

More in how many words a 2-year-old should say.

When it might be a real delay

Some bilingual children do have speech or language problems, just as some children who speak one language do. ASHA's key point: those problems show up in all their languages. A child who talks easily in one language but less in the other may simply have a leading language, which is normal. A child who is behind in every language deserves a check.

If you're worried, mention it at the next checkup and bring a list of the words your child says, in every language. Ask for:

• A hearing test, even if your baby passed the newborn screen.
• A speech-language evaluation, ideally with someone who can assess both languages, or who will count words in both.

Please don't drop a language to "fix" a delay. A child who is struggling still needs the rich, comfortable talk of the people who love them, in the language those people speak best.

How to raise a bilingual child well

Speak the language you're most comfortable in. Your richest, warmest, most fluent talk is what builds language. A parent who chats freely, sings and jokes in their first language gives a child far more than one who speaks a stiff second language "for school."

Pick a plan you can keep up. Many families use one parent, one language. Others use one language at home and another outside. The best plan is the one your family can keep up.

Keep it live. Language is learned from people. In a Seattle study, 9-month-olds who played with a live Mandarin speaker for about five hours learned Mandarin speech sounds; babies who got the same Mandarin from a DVD or audio learned nothing. Grandparents on video calls, songs, rhymes and books in the family language all help.

Use the same talk habits in every language. Expand what your child says, ask choice questions, name things and wait for their turn. Sing the rhymes you grew up with, too. Songs and rhymes in the family language carry rhythm, words and a bit of home all at once.

An honest note on the "bilingual brain boost"

You may read that bilingual children get sharper focus or more self-control. The best evidence doesn't back that up. A 2020 University of Oslo review of 143 comparisons found almost no overall difference in executive function (an effect size of 0.06, close to zero), with signs that exciting results were more likely to get published.

So raise a bilingual child for the language itself, the family ties and the culture: grandparents' stories, songs, jokes, and a sense of who your family is. Children who speak two languages get something better and more certain than a brain boost. They speak two languages.

Go deeper

Grow a Genius

In the book: Chapter 20: The Word Explosion

The book covers raising children in two or three languages, from the word explosion to adding a language at 3 to 6 in Chapter 25, with the talk habits that work in every language.

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