The advice to “speak only one language to them so they don’t get confused” has been passed down for decades. The research does not support it.
What the data shows
- Children growing up with two languages reach the core milestones — first words, first phrases, first sentences — on essentially the same timeline as monolingual children.
- Vocabulary in each language separately may be smaller, but added together across both languages the total is comparable or larger.
- Mixing languages within a sentence is normal among bilingual speakers, not a sign of a disorder.
How a real delay shows itself
In a bilingual child, a genuine speech and language disorder appears in both languages, not just one. If the child lags only in the language they hear less, that is usually a question of how much input they get, not of ability.
Practical advice
Parents should speak the language they are most expressive in. Switching to a language the parent commands less well reduces the quality and quantity of language input — exactly what the child learns from.
Sources
- American Speech-Language-Hearing Association — Bilingual Service Delivery, asha.org
- Speech Pathology Australia — bilingualism is not a risk factor for speech or language disorders.
- Journal of Speech, Language, and Hearing Research (2023) — Exploring assumptions of the bilingual delay.
This article is an informational summary of published research and does not replace an individual assessment.