Does Baby Sign Language Delay Speech?

"If your baby can just sign for what they want, why would they bother learning to talk?"

My mother-in-law asked me this the week I started signing with my daughter. A friend said something similar. I'd read it in a parenting forum too. It sounds logical. If signing works, what's the motivation to speak?

But it's wrong. And the research on this is not ambiguous.

Where this myth comes from

The concern makes intuitive sense, which is exactly why it persists. If a baby has a working communication system, the thinking goes, they'll lean on it instead of developing speech. Why struggle to say "milk" when a hand squeeze gets the job done?

There's also confusion between baby sign language and sign language used by deaf or hard-of-hearing children. Those are fundamentally different situations. Deaf children learning ASL as a primary language are on a different developmental path than hearing babies picking up a handful of signs while surrounded by spoken language all day.

And then there's coincidence. Babies typically start signing between 8 and 12 months, which is also when parents start watching for first words. If the signs show up but the words don't, it's easy to blame the signing. But correlation is not causation, and the research tells a very different story.

What the research actually shows

Linda Acredolo and Susan Goodwyn studied this question for over a decade. Their landmark study with Claire Brown, published in 2000, followed 140 families. Half taught their babies signs. Half didn't. The results were clear: signing babies had significantly larger spoken vocabularies at 24 months. That advantage held at 36 months.

Read that again. The babies who signed didn't just catch up. They were ahead.

Kirk, Howlett, Pine, and Fletcher confirmed this in 2013 with a more tightly controlled study. They found no negative effect of baby signing on verbal development. The trend was positive, consistent with Acredolo and Goodwyn's earlier findings.

Vallotton's 2012 research added an important piece of the puzzle. She found that babies use signs as "placeholders" while they build verbal language. A baby signs "dog" for weeks or months, and during that time they're building the cognitive framework for what "dog" means. When the spoken word becomes motorically easier, they switch. No intervention needed. No phase-out plan. They just start saying it instead.

Why signing supports speech

Every time you sign with your baby, you say the word out loud. That's the rule every signing program teaches, and it's the reason the research comes out the way it does. Your baby isn't choosing between signing and speaking. They're getting double the language input.

Signing also creates more conversational turns. Your baby signs "more." You say "More crackers? You want more crackers?" Your baby signs "more" again. That back-and-forth is the foundation of language development. Without signs, a pre-verbal baby's only tools are crying, pointing, and reaching. Signs turn those one-way signals into actual exchanges.

There's a deeper mechanism too. When a baby learns that a hand movement represents milk, they've grasped symbolic communication. That's the same cognitive leap required for spoken language. A sound represents a thing. Signs don't compete with that understanding. They build it.

My daughter signed "milk," "more," and "all done" for about three months before she said any of those words. When she did start speaking, the transition was seamless. She'd sign and say the word at the same time for a while, then gradually drop the sign. By 18 months, most of her signs were gone, replaced by words. She didn't need them anymore.

When to be concerned (and when not to)

Babies develop at different speeds, and some lean on signs longer than others. That's normal, not a red flag.

It's completely normal for a baby to prefer signing over speaking until 15 or even 18 months. Speech requires fine motor control of the tongue, lips, and breath. Hands are easier. Your baby isn't being lazy. They're using the tool that works best for them right now.

It's also normal for babies to temporarily drop a few words during developmental growth spurts and revert to signs. Language development isn't a straight line. There are plateaus and regressions.

What's worth a conversation with your pediatrician: no words and no signs by 18 months, or a loss of skills your baby previously had. Those concerns exist regardless of whether you've been signing. Signing doesn't cause them, and the absence of signing doesn't prevent them.

What pediatricians and speech therapists say

The American Academy of Pediatrics does not discourage baby sign language. Many pediatricians actively recommend it, particularly for the communication benefits during the frustrating pre-verbal months.

Speech-language pathologists go further. Many SLPs use signing as a therapeutic tool for late talkers, children with Down syndrome, and children on the autism spectrum. If signing delayed speech, therapists wouldn't be prescribing it. They use it specifically because it supports language development.

When I mentioned to our pediatrician that we were signing with our daughter, she didn't raise concerns. She asked which signs we'd started with and suggested adding "help" early. That was it.

The real risk is not signing

Here's what I think about when this question comes up. The concern is always "What if signing slows down speech?" But nobody asks the opposite question: "What if NOT signing means my baby has no way to communicate for months?"

A baby without signs has crying, reaching, and pointing. That's it. They can't tell you they're hungry, thirsty, tired, scared, or in pain. They can't tell you they want the book, not the ball. They can't tell you they're done.

That frustration is real, and it's daily. Signing doesn't just help with language development. It reduces tantrums, strengthens the parent-child bond, and gives your baby agency during a period when they have almost none.

Twenty years of research points in one direction. Signing supports speech. It does not replace it, delay it, or compete with it. The babies who sign end up with bigger vocabularies, not smaller ones. Every credible study confirms this.

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