The Benefits of Baby Sign Language

At nine months old, most babies can't say a single word. Some of them, if you've been showing them the vocabulary, can open and close one small fist when they want milk. Or tap their fingers together when they want more. Or wave a flat hand away from their chest to say they're finished.

This is the idea behind baby sign language. Not a formal language system. Not full American Sign Language taught properly, though some families go that route. Just a handful of simple gestures mapped to things babies want to talk about. Long before a baby can say a word, she can recognize it — and she can move her hands. Signing lives in that space.

Most parents who ask about signing want to know whether the benefits are real or oversold. Here is the short answer before the detail. The big promises don't survive testing: signing will not make your baby smarter and will not hand her a bigger spoken vocabulary, and the best-designed studies find no language advantage at all. Nothing suggests it does any harm either. What one careful trial did find sat on the other side of the high chair — the parents changed. They got better at reading what their baby was doing with her hands and her face. That's a smaller claim than the one on the box, and it's the one still standing.

The Gap Between Understanding and Speaking

By around eight or nine months, most babies understand a surprising amount of what you say. They know their name. They recognize “no.” They turn when you mention the dog or the bottle. Their receptive language — the part that takes words in — is weeks or months ahead of their productive language, the part that sends words out.

That mismatch shows up as frustration. A baby who clearly wants something but has no way to name it has to resort to pointing, fussing, or crying until the adult runs through the right guesses. Parents who've watched this cycle play out twenty times before dinner know exactly how exhausting it is for both sides.

Signs don't close the gap because babies learn to sign faster than they learn to speak. They close it because the motor system needed for a gesture matures earlier than the motor system needed for speech. Shaping a hand into a sign is easier than coordinating lips, tongue, breath, and vocal cords to produce a word. Hands come online before mouths do. That's the whole mechanism — and, as the numbers further down show, it still takes longer than most signing programs let on.

What the Research Actually Shows

Nearly every claim you will read online traces back to one research group. Linda Acredolo at UC Davis and Susan Goodwyn at Cal State Stanislaus began documenting infant gestures in the 1980s, then ran a training study that followed 103 babies from eleven months to age three. Their published results did favor the signers. On an expressive vocabulary test at twenty-four months, the sign-trained children scored at roughly a twenty-seven-month level against twenty-four months for the babies whose parents had been told nothing.

Three months of expressive language. Not a transformation, and nowhere near the “two to three times more words” figure that circulates on signing websites, which appears nowhere in the paper.

Two things about that study are worth knowing before you weigh it. Acredolo and Goodwyn went on to build a commercial baby-signing program, so the most enthusiastic evidence and the products it sold came from the same desk. And a 2005 review in the journal First Language, by Johnston, Durieux-Smith and Bloom, examined seventeen studies of infant signing, theirs included, and found that not one was a randomized controlled trial — many did not even report how families had been assigned to groups. The famous IQ number has a similar shape. A twelve-point advantage at age eight, presented by the same two researchers at a 2000 infancy conference, was never published in a peer-reviewed journal, and fewer than two-thirds of the original children could be traced that far.

Then came a trial built to settle it. Psychologists at the University of Hertfordshire randomly assigned forty mother-baby pairs to four groups — one taught British Sign Language signs, one taught the invented symbolic gestures that commercial programs use, one simply asked to say the same ten target words often, and one told nothing at all — and followed every baby from eight months to twenty months. Their finding, in their own words, was that infants exposed to gesture “did not differ from control conditions on language outcomes.” This wasn't an early advantage that faded. There was no advantage at any age tested.

Bigger and later work points the same way. A systematic review in First Language (Fitzpatrick and colleagues, 2014) screened more than nineteen hundred citations, kept the ten studies that met its standards, and concluded that the effectiveness of baby sign “remains unclear” — while finding nothing at all to suggest it interferes with development. Then in 2026, in the same journal, Bertussi and colleagues compared 723 French toddlers whose families signed with 625 who didn't. That is the largest sample anyone has assembled, and once family background was accounted for, the effect on vocabulary came out weak to none.

So why does anyone still recommend it? Because the Hertfordshire team filmed the families as well as testing the babies, and the film showed something the language tests couldn't. Mothers who had been taught to sign responded more often to their infants' nonverbal cues and left more room for the baby to act on her own. The training didn't change the children's language. It changed how closely the adults were watching.

That is a modest result, and it is the honest case for trying signing. A parent scanning for one small hand to move is a parent noticing a great deal else besides. No IQ boost. A calmer kitchen floor at dinnertime, arrived at from an unexpected direction.

When Babies Can Actually Start Signing

You can start showing signs much earlier than a baby can produce them. Many families introduce their first two or three signs around six months, alongside the start of solid foods. The baby won't sign back for a while. That's fine. The exposure phase is normal and important.

Expect it to take longer than the marketing implies. Mothers in the Hertfordshire trial began modeling ten signs at eight months. At ten months their babies were producing, on average, essentially none. At twelve months, one or two. Only between twelve and sixteen months did the repertoire open up, climbing to an average of six or seven signs.

So if you start at six months and see nothing back for a season, nothing has gone wrong. That is simply what the curve looks like. And like almost everything in the first year of infant development, the spread between babies is wide: signing at eight months isn't giftedness, and waiting until fourteen isn't a delay.

What you're watching for isn't a perfect reproduction of the sign. Early attempts are approximations. The “milk” sign — one hand opening and closing — usually looks more like a general fist-clench at first. The “more” sign — fingertips tapping together — often comes out as two flat hands patting each other. If the gesture happens in the right context and you respond, the baby has made a communicative move. The motor refinement follows over weeks.

The Handful of Signs That Do the Most Work

You don't need to teach dozens of signs to see the benefit. A small core set — five to eight signs that cover the most common daily requests and observations — gives a baby most of the usable vocabulary she needs in the pre-verbal window.

The signs families find most useful tend to cluster around a few themes:

• Feeding: milk, water, eat, more, all done
• Daily care: sleep, diaper, bath, help
• People and things she notices: dog, cat, bird, book, light
• Feelings she can flag: hurt, hot, cold

“More” and “all done” are often the first two families teach, because they're useful at every meal and they're easy for small hands to form. “Milk” is a strong third, since most babies have a lot to say about milk. “Help” and “hurt” come later but matter disproportionately. A twelve-month-old who can tell you her foot hurts because a sock seam is digging in is a twelve-month-old who doesn't have to cry for forty minutes first.

You can borrow signs from a real sign language, which is what most baby-signing books adapt, or make up your own. This is the one design question the Hertfordshire trial settled outright: babies picked up formal British Sign Language signs and invented symbolic gestures at the same rate, and neither type changed a single language outcome. So choose on practical grounds. Real signs have the advantage that other people may recognize them — a grandparent or a daycare provider can pick up a few without coaching.

How It Actually Looks in Daily Life

The way most families teach signs isn't through sit-down lessons. It's through steady repetition inside the moments where the word naturally comes up.

You sign “milk” while you say “milk” and hand over the bottle. You sign “more” while you say “more” when you give a second spoonful. You sign “all done” while you say “all done” at the end of the meal and lift her out of the high chair. The baby sees the sign hundreds of times, paired with the object and the word, before she tries to produce it herself.

Two small habits make the learning stick. Use the sign in full view of the baby, not off to the side. And always pair it with the spoken word — never sign silently, hoping she'll pick up just the gesture. Signs are not a replacement for talking. They're a second channel, open while the vocal one is still under construction.

No signing program has yet outperformed the ordinary thing it sits inside: an adult who talks to a baby, watches what the baby does next, and answers it.

This is also why the worry that signing might delay speech can be set down. Signing babies start talking on the same schedule as everyone else; that much has held across every study that looked, including the ones that found no benefit whatsoever. Nothing is being traded away.

What Signing Doesn't Do

Honest expectations go a long way here. Nothing about signing turns a baby verbal earlier in any dramatic sense. It will not give her a measurable cognitive edge that lasts into preschool. It will not make the second half of her first year tantrum-proof.

What it does give you is a shared channel during the months when your baby clearly wants to tell you something and has no reliable way to do it. Whether that measurably lowers the household frustration level is not something anyone has demonstrated; what families describe is that it changes the texture of those exchanges. Parents often describe the moment their child made her first successful sign as surprisingly emotional — a small but unmistakable sense of her coming into focus as someone with opinions and preferences she can now share.

A few families try signing and drop it after a month or two because they don't see progress. That's common and not a failure. Some babies take much longer to show a sign back. Some families find the daily effort doesn't match the payoff for their particular household. Both are fine outcomes. Signing is an optional tool, not a developmental requirement.

When to Ease Off

Most families naturally retire baby signs somewhere between fifteen and twenty-four months, as spoken words start to take over. The baby may keep using the occasional sign for a month or two longer, especially for favorites like “more,” but the overall pattern is that signs fade as speech arrives.

You don't need to actively stop signing. The baby drops what she doesn't need. If you find your toddler still using a sign long after she could say the word, she's probably using it the way adults use hand gestures — for emphasis, or to make sure she's heard. That's normal, and there's no developmental concern in continuing.

One caveat matters more than all the others. Families often ask whether signing is the answer for a toddler who isn't talking yet. Gestures do matter here — but as a signal, not a home remedy. The guidance for families from speech-language pathologists (SLPs) — published by the Communication Health Support Association and powered, in its own words, by the expertise of the American Speech-Language-Hearing Association — says that between eighteen and thirty months a child who uses plenty of gestures is more likely to catch up with peers, and that limited gesture use may signal a need for extra support.

The same guidance is blunt about timing: you do not have to “wait and see” before talking to an SLP. If how your child communicates is worrying you, that conversation belongs now, not at a milestone birthday. Signs can be part of a support plan — clinicians use them — but never a substitute for the assessment that shapes it, especially when a child isn't following the expected arc of early language development.

Fitting Signing Into the Bigger Picture

Signing works best when it sits inside a broader rhythm of talking, reading, and responsive interaction. A baby who is signed to and also talked to, read to, and listened to will do well. A baby who is signed to in silence, with everything else stripped out, won't get the same benefit — because signs were never the main engine. The main engine is language exposure of every kind.

Reading is a natural pairing. Picture books full of animals and daily objects are a low-effort way to practice signs in context. Point to the dog on the page, sign “dog,” say “dog.” A short list of activities that support infant language development overlaps almost perfectly with the moments where signing slots in naturally.

The same goes for play. Floor time, peekaboo, the small daily loops that babies love — these are all places where a sign can land. You don't need a separate curriculum. Our Milestone Tracker can help you see where your baby is in the broader language and motor arc, which makes it easier to judge whether introducing signs now makes sense or whether she's still a few weeks out.

Parents who've been studying their baby's cues closely are often already halfway to signing without knowing it. If you've been working on how to read your baby's different cries, you've been building exactly the pattern-recognition skill that makes signing click. Signs are just a structured extension of that same two-way reading.

Frequently Asked Questions

Does baby signing delay speech?

No, and this is the one question the research answers cleanly. The systematic review described above turned up no evidence that baby sign interferes with typical development. In the randomized trial, signing babies picked up the ten target words on the same schedule as the babies whose mothers had been coached to repeat those exact words all day — and matched the babies whose mothers were told nothing at all. Older work from the Acredolo group found a small vocabulary edge in the second year; newer and larger work doesn't. Either way, nobody has found a cost.

What age should I start?

Six to eight months is when most families start showing signs, because that's when babies begin paying real attention to hand movements and starting solids (which gives “more” and “all done” an immediate daily use). Budget several months before anything comes back. In the trial described earlier, babies whose mothers began at eight months were still producing almost nothing at ten months and only one or two signs at their first birthday. Starting at nine or ten months isn't too late either — nothing in the evidence rewards starting earlier.

Do I need a book or a class, or can I just pick up a few signs online?

For a starter set of five to ten signs, a short online tutorial or a diagram chart is usually enough. Most parents don't need a full class. If you want to use real ASL accurately, or if you're planning to sign with a child who is deaf or hard of hearing, seek out a certified ASL instructor or a speech-language pathologist. That's a different situation with different standards. For typical hearing babies learning a handful of request-signs, consistency at home matters more than formal instruction.

My baby is fourteen months old and still not signing. Is something wrong?

Almost always, no. Plenty of babies never take to signing even when it's offered daily, because they already have strategies that do the same work — pointing, pulling you toward what they want, sound patterns of their own. Watch the gestures rather than the signs: a fourteen-month-old who points, waves, shows you things and shakes her head is doing exactly the thing speech-language pathologists treat as a good sign. If spoken language is also arriving on the usual schedule and she's socially engaged in other ways — eye contact, babbling with inflection, responding to her name — there's no cause for concern. What deserves a call is the opposite picture: few gestures, little apparent understanding, no new words accumulating. Raise that with your pediatrician or an SLP promptly, rather than after another six months of waiting.

Medical Disclaimer: This article is for informational purposes only and is not a substitute for medical advice. Baby signing is not a treatment for a speech or language delay. If anything about how your child hears, understands, or communicates concerns you, raise it with your pediatrician or a speech-language pathologist now rather than waiting to see whether she grows out of it.