Speech Delay or Autism? How to Tell the Difference

The short answer: A speech delay means a child is learning to talk later than expected. Autism is broader: it affects how a child connects and communicates with others, and it usually comes with repetitive behaviors or sensory differences too. The biggest clue is often what a child does without words. Many late talkers point, wave, bring you things to show you and look to your face to share a moment. Autistic toddlers more often communicate in other ways. The two can also happen together, and only an evaluation can tell you which is which.

If you're asking this question, you've probably been watching closely for a while. That's not overthinking. That's paying attention, and it's exactly how most families find the right support.

How common are late talkers?

Very common. Between 10% and 20% of 2-year-olds are late talkers, according to the American Speech-Language-Hearing Association (ASHA). About half to two-thirds of them catch up with their peers by the late preschool or early school years. Children who have trouble understanding words, not just saying them, are less likely to catch up on their own.

Talking milestones to know

These come from the CDC's milestone checklists. Each one is something at least 75% of children can do by that age, so missing one is a reason to ask, not a reason to panic.

• By 18 months: tries to say three or more words besides "mama" or "dada," and follows one-step directions without gestures, like handing you a toy when you ask.
• By 2 years: says at least two words together, like "more milk," points to things in a book when you ask, and uses gestures beyond waving and pointing, like blowing a kiss or nodding yes.
• By 30 months: says about 50 words and puts two or more words together with an action word, like "doggie run."

For the full list, see our guide to toddler milestones.

Speech delay or autism: what to look for

Words are only one part of communication. Clinicians look closely at everything else a child does to connect with you.

More typical of a speech delay alone

• Uses gestures to make up for missing words: pointing, waving, showing, nodding or shaking their head.
• Points to share something interesting, not only to ask for things.
• Looks at your face to share excitement or to check how you're reacting.
• Shares attention with you: looks at what you point to, then back at you.
• Plays pretend, like feeding a doll or talking on a toy phone.
• Understands more than they can say.

More typical of autism

• Fewer gestures, or gestures mostly used to get needs met. For example, leading you by the hand to what they want instead of pointing.
• Less sharing of attention: not pointing to show you things, or not following your point.
• Less pretend play, or play that focuses on lining up, spinning or sorting.
• Repetitive movements or routines, like hand flapping or needing things done the same way. Read more about hand flapping.
• Sensory differences, like strong reactions to sounds, textures or lights, or seeking out certain sensations.
• Losing words or skills they used to have. This happens for some autistic children between 15 and 24 months.

No single sign means a child is or isn't autistic. Lots of late talkers have one or two traits from the second list, and some autistic children have plenty from the first. That's why the full picture matters more than any checklist.

Can a child have both?

Yes. Many autistic children also have a language delay or language disorder, and some children who start out as late talkers are later diagnosed with autism. A speech delay doesn't rule autism out, and an autism diagnosis doesn't mean speech therapy isn't needed. Many children benefit from both.

What to do if you're not sure

You don't have to "wait and see." Getting it checked gives you a plan, whatever the answer turns out to be. If an evaluation shows a simple delay, watching closely may be part of that plan, but it will be a plan, not a guess.

• Start with your pediatrician. Share what you're noticing and ask about a hearing test, since hearing affects speech. Ask about autism screening too. Pediatricians commonly screen at the 18- and 24-month visits, and our guide to the M-CHAT-R screener explains how it works.
• Get a speech and language evaluation. A speech-language pathologist (SLP) can measure what your child understands and says, and how they use gestures and play to communicate.
• Ask about an autism evaluation if other signs fit. A developmental pediatrician, psychologist or neuropsychologist can evaluate for autism, often with a team.
• Contact early intervention if your child is under 3. Every state offers it, and you don't need a diagnosis or a doctor's referral to ask for an evaluation. See our guides to Early Intervention in Illinois and ECI in Texas.

Where we can help

Our speech-language pathologists work side by side with our ABA, occupational therapy and evaluation teams, so if speech is only part of the picture, your child doesn't have to start over with a new provider.

• Illinois: speech therapy at our Naperville, Woodridge and Elmhurst centers, and early autism testing in Naperville.
• Texas: speech therapy at our Keller and Southlake centers.

Common questions

How can I tell if my child has a speech delay or autism?

Look at how your child communicates without words. Children with a speech delay alone usually point, gesture, share attention and play pretend. Autistic children more often show differences in these social skills, along with repetitive behaviors or sensory differences. An evaluation is the only way to know for sure.

Is it normal for a 2-year-old not to talk?

Between 10% and 20% of 2-year-olds are late talkers, and many catch up. By age 2, most children say at least two words together. If yours isn't, it's worth talking to your pediatrician and asking about a speech evaluation.

Can a speech delay be the only sign of autism?

It's uncommon for a speech delay to be the only difference in an autistic child. Clinicians usually also see differences in gestures, shared attention, play or behavior. If you're unsure, an evaluation can look at the whole picture.

Do late talkers catch up?

About half to two-thirds of late talkers catch up by the late preschool or early school years. Children who also have trouble understanding language are less likely to catch up without support.

Should I wait and see?

You don't have to. An evaluation won't hurt, and it gives you clear answers and a plan sooner.

Sources: CDC "Learn the Signs. Act Early." milestone checklists (2022 update); American Speech-Language-Hearing Association, Late Language Emergence and Autism practice portals; American Academy of Pediatrics, HealthyChildren.org pages on language delay and early signs of autism.