The best time to start Spanish with your baby is now — from birth, in everyday moments. There's a special window for learning the sounds of a language around 6 to 12 months, but it isn't a door that slams shut. Children begin heritage languages at one, two, three and beyond and become beautifully bilingual.
Babies are born "citizens of the world"
Newborns can distinguish the sounds of every human language — a baby born in Bogotá can hear distinctions in Mandarin most adults can't. Researchers call this universal phonetic sensitivity (Werker & Tees, 1984; Kuhl et al., 1992).
What happens at 6–12 months
Over the first year, a baby's brain tunes to the languages it actually hears — perceptual narrowing. The ability to tell apart sounds from unheard languages fades while heard sounds sharpen (Werker & Tees, 1984). The encouraging part for bilingual families: babies hearing two languages keep both sound systems (Burns et al., 2007).
Why your voice is the active ingredient
Babies who heard a new language from a live person learned its sounds — but babies who got identical lessons through audio or video learned nothing (Kuhl, Tsao & Liu, 2003). Language is "socially gated," which is why a screen can't do this and you can.
But it's a window, not a deadline
The honest science: this window is about sound. Vocabulary, grammar, and cultural-linguistic identity develop across years. If your baby is past their first birthday, you've missed nothing — start today and keep going.
For the full developmental picture, see How Does a Child Become Bilingual?
- Werker, J. F., & Tees, R. C. (1984). Cross-language speech perception. Infant Behavior and Development, 7(1), 49–63.
- Kuhl, P. K., Williams, K. A., Lacerda, F., Stevens, K. N., & Lindblom, B. (1992). Linguistic experience alters phonetic perception in infants by 6 months of age. Science, 255(5044), 606–608. https://doi.org/10.1126/science.1736364
- Kuhl, P. K., Tsao, F. M., & Liu, H. M. (2003). Foreign-language experience in infancy. PNAS, 100(15), 9096–9101. https://doi.org/10.1073/pnas.1532872100
- Burns, T. C., et al. (2007). Phonetic representation in bilingual and monolingual infants. Applied Psycholinguistics.