Autism Diagnosis Checklist: Signs, Symptoms, and Next Steps

An autism diagnosis checklist lists the behaviors doctors look for when they check a child for autism. It's based on the DSM-5 diagnostic criteria, the rules doctors use to diagnose autism. A checklist can't diagnose autism, and only a qualified professional can make that call after an evaluation.

Many parents notice differences in their child's development long before anyone has clear answers. What you see may not match what other parents describe, and autism looks different in girls. You can use a checklist to write down what you see at home and share it with your child's doctor.

Key takeaways

• A checklist organizes what you see: It helps you notice common behaviors and describe them clearly to a doctor.
• A professional makes the diagnosis: A trained clinician decides after talking with you and watching your child.
• Doctors look at two groups of signs together: They look for social differences plus repeated behaviors or intense interests in more than one setting.
• Help is there after a diagnosis: Alpaca Health can match your family with an in-network behavior analyst when you start your intake.

What is an autism diagnosis checklist?

It's a list of behaviors to watch for, sorted by the areas doctors check. It can help you learn the earliest signs of autism in babies and toddlers. As you read about autism, you'll see three terms that are easy to mix up:

• Screening tool: A short questionnaire that shows whether your child would benefit from a closer look. Screening tools do not result in diagnoses, according to the Centers for Disease Control and Prevention (CDC). A positive result should lead to a full assessment.
• Diagnosis: A formal label that a medical professional gives to explain what's causing your child's signs.
• Checklist: A list of behaviors to watch for in your child. It helps you organize what you see so you can explain your concerns clearly.

A checklist is the simplest of the three, and you can start one today. Your notes give the clinician at a screening or evaluation a fuller picture of your child's day.

You don't have to figure this out alone.

Alpaca Health matches your family with a vetted, in-network BCBA. We handle the insurance paperwork so you can focus on your child.

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What do doctors look for to diagnose autism?

Doctors look for two groups of signs: differences in social communication and repeated or restricted behaviors. A diagnosis usually relies on two sources of information. One is your description of how your child has developed, and the other is a professional's observation of your child. No single test makes the diagnosis on its own.

The rules come from the American Psychiatric Association's diagnostic manual, the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).

The rule in the CDC's summary of the criteria, reviewed in May 2025, has two parts. A child must have lasting difficulties in each of the three areas of social communication and interaction. They must also have at least two of the four types of restricted, repetitive behaviors.

The table below puts the five criteria, labeled A to E, into everyday words, with one example for each:

When a child meets the criteria, the clinician also records a level of support from 1 to 3. Each of the two groups of signs gets its own level.

Older labels such as Asperger syndrome are now part of one diagnosis, autism spectrum disorder. So is pervasive developmental disorder not otherwise specified (PDD-NOS).

Autism symptoms checklist

Each item matches one DSM-5 area and has a short list of things you may have seen. Tick the ones you notice often and in more than one place, then bring the list to your child's doctor.

Lack of social or emotional reciprocity

Social and emotional reciprocity is the everyday back-and-forth of how children interact with others. It includes responding to other people's feelings, joining a conversation and paying attention to others during play.

For example, your child may not show you a toy they love, or rarely smile or laugh when you try to be funny. Another early sign is not responding to their name by 9 months of age.

For this checklist item, consider if you've often noticed your child:

• Seem uninterested in social interaction, or not respond when others try to engage them.
• Not share interests, enjoyment or accomplishments with others.
• Not return smiles, sounds or facial expressions during back-and-forth play.

Limited nonverbal communication

Nonverbal communication is the part of an exchange that doesn't use words, like eye contact, facial expressions, gestures and body language. Children usually learn to communicate this way long before they talk. Autistic children often use less nonverbal communication.

These differences tend to be steady, though they can be subtle. For example, your child may look away when you talk to them, or rarely point to show you something they like.

For this checklist item, consider if you've often noticed your child:

• Avoid eye contact or make very little of it.
• Show facial expressions that don't match the situation, or very few at all.
• Rarely use gestures like pointing or waving.

Difficulty developing or maintaining relationships

This item is about how your child gets along with other children and adjusts to different social settings. Social demands grow as children get older, which can make some social difficulties easier to see. They can look very different in a toddler than in a school-age child.

For example, a three-year-old may not notice other children at the playground. An older child may want friends but struggle to make or keep them.

For this checklist item, consider if you've often noticed your child:

• Prefer to play alone instead of with other children.
• Have trouble adjusting their behavior to different social situations.
• Show little interest in their peers or in pretend play with others.

Repetitive movements, speech, or behaviors

Your child may do the same actions or patterns over and over. These behaviors can help some children calm down, especially when they feel overwhelmed. They become more of a concern when they happen more often, get more intense or make daily life harder.

For example, your child may flap their hands when excited or repeat phrases they heard earlier. Lining up toys and getting upset when the order changes is another common example.

For this checklist item, consider if you've often noticed your child:

• Repeat words or phrases without a clear purpose in the conversation (this is called echolalia).
• Play with toys the same way every time, or use them in ways that don't match their purpose.
• Flap their hands, spin, rock or make other repeated body movements.

Insistence on sameness or difficulty with change

Many autistic children have a strong need for routines and predictability. They can get very upset when a routine changes or something interrupts it.

For example, your child may want the same food or the same show every day. A small change to that plan can lead to a meltdown.

For this checklist item, consider if you've often noticed your child:

• Get upset by small changes to their routine or surroundings.
• Insist on the same daily routines and rituals.
• Have trouble moving from one activity to the next.

Intense or unusual interests

Some autistic children have interests that are unusually intense or narrow, which the DSM-5 criteria describe as fixated interests. Common examples include a strong focus on one topic or on parts of objects.

For example, your child may spin the wheels of a toy car for a long time instead of driving it. They may also carry the same unusual object everywhere and get very upset without it. Many children have favorite topics, and a doctor will ask how strong the interest is and how much of the day it takes up.

When you look at this item, think about whether your child often seems to:

• Focus on one topic or object far more than other children their age.
• Hold on to an unusual object, like a piece of string or a jar lid.
• Pay close attention to parts of objects, such as wheels or light switches.

Sensory sensitivities or sensory-seeking behaviors

Some children react very strongly to light, sound or textures. Others seek out strong feelings through touch, smell or exploring objects. These sensory processing differences are common in children with autism.

For example, your child may hate how certain clothes feel or how bright a room is. Another child may not seem to notice pain, heat or cold.

For this checklist item, consider if you've often noticed your child:

• Have strong reactions to sounds, lights, textures or smells.
• Show discomfort with certain clothing, foods or places.
• Seek strong sensations like spinning, touching objects or mouthing items.
• Seem not to notice pain, heat or cold.

Language and communication delays

Language delays are common in autistic children, though they aren't one of the DSM-5 criteria. Delayed language is one of the other characteristics many autistic children have. Late talking on its own can also have other causes, such as a hearing problem.

Toddlers at higher likelihood of autism tend to score lower on language and gesture measures than other toddlers. Delays can affect understanding, speaking or both. For example, your child may use only a few words, or may speak very fast or very slowly.

For this checklist item, consider if you've often noticed your child:

• Have delayed speech or limited vocabulary for their age.
• Use speech unevenly, or stop using words they used before.

Which signs show up at which age?

Several social signs are tied to the age when most children pick up that skill. The table below lists them as the CDC's signs and symptoms page gives them, as of November 2026. Autistic children may not show all or any of these signs, so treat each row as something to raise with your doctor.

Six of the ten signs come before age 2. Many early signs of autism can show up in the baby and toddler years, when your child sees the pediatrician often.

How to use an autism checklist to support your child

An autism checklist works best when you fill it in over several days to a few weeks. It helps you speak clearly if you decide to see a pediatrician or specialist.

Challenges that show up in more than one setting, such as at home and around other people, tell a doctor more than a single moment does. Research shows parents are reliable sources of information about their child's development, so your notes matter.

A simple framework for documenting what you observe looks like this:

Take some time to observe your child using this framework. If you notice challenges in several areas, it may be time to talk with a professional about an evaluation.

Ask your child's teacher or child care provider what they see too. They see your child in a group, which is a setting you don't often get to watch. You can also keep a record with the CDC's milestone checklists, which cover ages 2 months to 5 years.

Which screening tools can parents use?

Your pediatrician may already use a screening tool such as the Modified Checklist for Autism in Toddlers, Revised (M-CHAT-R) at well visits. As of October 2026, the American Academy of Pediatrics (AAP) recommends autism screening for every child at 18 and 24 months. It also recommends general developmental screening at 9, 18 and 30 months.

If your child's doctor doesn't screen at these visits, you can ask for it. Screening can also happen at other ages whenever you or your doctor has a concern.

The M-CHAT-R asks 20 yes or no questions. Its official instructions, dated March 2025, say it's valid for toddlers 16 to 30 months old.

You can take the free M-CHAT-R screener at home and bring the result to your doctor. The same instructions explain what each total score means:

The M-CHAT-R is built to catch as many autistic children as possible, so it also flags many children who turn out not to be autistic. Those children are more likely to have another developmental delay, and the authors say any child who screens positive should have an evaluation. If you or your doctor are worried about autism, they also advise an evaluation whatever the score.

For older children, the free CAST questionnaire, short for Childhood Autism Spectrum Test, asks a parent 37 yes or no questions. The Alpaca Health screener page lists it for children 4 to 11 years old.

When to talk to a doctor or specialist

Make an appointment with your child's pediatrician once you've seen several behaviors on the checklist. A pediatrician or another expert can give a formal autism diagnosis. When you describe what you've seen, it helps them understand how best to care for your child.

A formal evaluation is done by one or more trained specialists. They may include a developmental pediatrician, a child psychologist, a speech-language pathologist or an occupational therapist. The cost of an autism diagnosis can vary a lot, depending on where you live and your insurance.

Early evaluation matters because support can begin before a formal diagnosis. The Individuals with Disabilities Education Act (IDEA) is the federal special education law.

Under it, early intervention serves children under 3. Public schools serve children with disabilities ages 3 through 21. The same law's Child Find rule requires states to find and evaluate children who may have a disability.

To ask for an evaluation, the CDC's early intervention guidance, reviewed in February 2026, gives these steps:

• If your child is under 3: Call your state's early intervention program and ask for an evaluation. You don't need a doctor's referral or a diagnosis.
• If your child is 3 or older: Call any local public elementary school, even one your child doesn't attend. Ask to have your child evaluated through the school system for preschool special education services.
• If your child is in school: Ask the school's special education team about an evaluation. Caregivers and teachers are often first to notice signs in older children.

Above all, trust your instincts as a parent, and keep asking for help if your concerns don't go away.

What to bring to an autism evaluation

Bring your own notes along with reports from the people who see your child often.

The evaluation is likely to include a long talk with you about your child's behavior and development. Expect questions about daily skills like eating, dressing and toileting, and about family history. It may also include a hearing test or blood tests.

Before the appointment, gather these:

• Your filled-in symptom checklist and your observation notes.
• Screening results with the date, such as your child's M-CHAT-R score.
• Notes on when your child reached milestones, or which ones they haven't reached yet.
• Family history of autism, learning disorders, intellectual disability or attention-deficit/hyperactivity disorder (ADHD). The CDC asks parents to share these with the doctor.
• Reports from child care, preschool or school, and any therapy or early intervention reports.
• Short videos of behaviors you're worried about, in case your child doesn't show them in the office.
• A list of your questions.
• Your insurance card and any referral paperwork.

To keep everything in one place, you can download the printable checklist. It's a free PDF you can share with caregivers and bring to pediatric or evaluation appointments.

If the evaluation ends in a diagnosis, ask for a copy of the written report. You'll need it for the next steps after diagnosis.

How Alpaca Health helps families with evaluation and care

Alpaca Health helps your family get in touch with local providers who offer autism evaluation and care by streamlining some of the more complicated parts of the process, such as assessments, documentation, and coordination.

Organized and well-supported providers can provide clearer communication and smoother care experiences for you and your family.

ABA therapy, or Applied Behavior Analysis, is a therapy approach that can help your child learn new skills and reduce challenging behaviors. With Alpaca Health, ABA therapy can fit around your family's schedule, with care at home or in an office.

If your child has a diagnosis and you're ready for ABA, you can begin your intake. Alpaca Health will match your family with an in-network Board Certified Behavior Analyst (BCBA).

You don't have to figure this out alone.

Alpaca Health matches your family with a vetted, in-network BCBA. We handle the insurance paperwork so you can focus on your child.

Get matched with a BCBA →

FAQs about autism diagnosis checklists

How reliable is an autism diagnosis checklist?

An autism diagnosis checklist is reliable for what it's designed to do. It helps you organize what you see and explain it clearly to a professional. It can't diagnose autism, and no single tool should be the basis for a diagnosis.

What does it mean if my child meets several items on an autism checklist?

It means your child may benefit from a screening or an evaluation, especially if the items fall in several categories. A diagnosis needs lasting difficulties in all three areas of social communication and interaction. It also needs at least two of the four types of restricted, repetitive behaviors.

How many signs should raise concern when using an autism checklist?

There's no set number of signs. What matters more is whether the signs overlap across several items and keep happening. A few one-off behaviors tell a doctor less.

What are the 5 criteria for autism?

The five DSM-5 criteria start with differences in social communication and with restricted or repetitive behaviors. The signs must also start in early childhood and affect daily life. Last, intellectual disability or a general developmental delay can't explain them better.

What age is autism usually diagnosed?

In CDC surveillance data published in April 2025, the median age at earliest known diagnosis was 47 months, or almost 4 years. That figure is for 8-year-olds with autism in 2022. A diagnosis by an experienced professional can be reliable by age 2, though many children aren't diagnosed until much later.

What should parents do after completing an autism checklist?

Share the checklist with your child's pediatrician and ask about a screening and an evaluation. If your child is under 3, you can also call your state's early intervention program yourself. If your child is diagnosed and you want help starting ABA, you can get matched with a BCBA through Alpaca Health.