Screening & Diagnosis


Identifying Autism


When family members or support providers become concerned that a child is not following a typical developmental course, they turn to experts, including psychologists, educators and medical professionals, for a diagnosis.

At first glance, some people with Autism may appear to have an intellectual disability, sensory processing issues, or problems with hearing or vision, and the diagnosis of Autism may become more challenging.

These conditions can co-occur with Autism and it can be confusing to families when they receive multiple diagnoses. However, it is important to identify Autism, as an accurate and early Autism diagnosis can provide the basis for appropriate educational and home-based support.

There are many differences between a medical diagnosis and an educational determination, or school evaluation, of a disability.

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Medical Diagnosis

A medical diagnosis is made by a psychologist, developmental pediatrician, or other specialized physician based on an assessment of symptoms and diagnostic tests. A medical diagnosis of Autism spectrum disorder is most frequently made according to the Diagnostic and Statistical Manual (DSM-5, released 2013) of the American Psychiatric Association. This manual guides physicians in diagnosing Autism spectrum disorder according to a specific set of criterion.
A brief observation in a single setting cannot present a true picture of someone’s abilities and behaviors. The person’s developmental history and input from parents, caregivers and/or teachers are important components of an accurate diagnosis.

Educational Determination

An educational determination is made by a multidisciplinary evaluation team of various school professionals. The evaluation results are reviewed by a team of qualified professionals and the parents to determine whether a student qualifies for special education and related services under the Individuals with Disabilities Education Act (IDEA) (Hawkins, 2009).

An educational determination can qualify an individual for support within school settings. However, an educational determination is not the same as a medical diagnosis, and often will not qualify an individual for therapies and support outside of school that would typically be covered by insurance or Medicaid. Additionally, a medical diagnosis of Autism does not guarantee an educational determination.


Early identification is associated with dramatically better outcomes for people with Autism. The earlier a child is diagnosed, the earlier they can begin benefiting from early intervention therapies and education.

The Centers for Disease Control and Prevention’s National Center on Birth Defects and Developmental Disabilities (NCBDD) recommends that all children be screened for Autism by their family pediatrician three times by the age of three – at nine, 18, and 24 or 30 months. Intervention should start when an Autism diagnosis is suspected, rather than when a formal diagnosis is made.

The advantages of early intervention cannot be overemphasized. Children who receive early intervention

can make tremendous strides in their overall skill development, leading to improved quality of life.

The CDC provides a wealth of information on the early signs of Autism through its “Learn the Signs. Act Early” initiative.

While there is no one behavioral or communication assessment that can detect Autism, several screening instruments have been developed for use in determining if a child might need further evaluation for developmental delay and/or Autism, including the Ages and Stages Questionnaire (ASQ) and the Modified Checklist for Autism in Toddlers (M-CHAT). For detailed information about these instruments and the research behind them, click here.

There are no medical tests, such as blood work or brain scans, for diagnosing Autism. An accurate medical diagnosis must be based on observation of the individual’s communication, social interaction, and their activities and interests.


Medical professionals who may have experience with Autism and other neurodevelopmental disorders include pediatricians (especially developmental pediatricians), neurologists, psychiatrists and psychologists. Not every one of these professionals has experience with Autism, so you should seek recommendations of knowledgeable professionals in your area from:

  • Your local Autism Society affiliate
  • Autism support groups
  • People who have children or other family members with Autism
  • Your primary care provider

A skilled practitioner can begin the assessment; the evaluation itself can vary depending on the professional administering it, the age of the person being assessed, the severity of his or her needs, and local available resources. A medical assessment for Autism typically includes:

  • A medical history of the mother’s pregnancy
  • Developmental milestones
  • Sensory challenges
  • Medical illnesses, including ear infections and seizures
  • Any family history of developmental disorders
  • Any family history of genetic and metabolic disorders
  • An assessment of cognitive functioning
  • An assessment of language skills
  • An Autism-specific observational test, interview or rating scale
Medical Diagnosis

While there is not a single behavioral or communication test that can detect Autism, several Autism-specific tools are now being used for formal diagnosis. These include the Autism Diagnostic Observation Schedule, Second Edition (ADOS™-2), the Autism Diagnostic Interview (ADI), the Screening Tool for Autism in Toddlers (STAT), the Childhood Autism Rating Scales (CARS), and the Tele-ASD-Peds for diagnosis for use in telehealth. All of these tests should be used as part of a larger assessment, and not just on their own, as the determination of Autism is best completed with multiple sources of information.

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Diagnosis Per
Life Stage

Evaluations typically begin with your primary care provider and vary based on age. If your primary care professional does not wish to refer you to a diagnostician, or does not acknowledge your concerns, it is important to know that you have the right to contact a diagnostician for a second opinion. Check the website of your local Autism Society affiliate for information about diagnosticians in your area, or call our team of national Information & Referral specialists at
800-3-AUTISM (800-328-8476).

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Infant and Toddler

Infant and toddler diagnosis begins with voicing your concerns with your child’s pediatrician or primary care doctor. A primary care professional should be able to review your child’s development and conduct a short Autism screening. If that screening indicates that Autism might be a possibility, the doctor may diagnose your child if they have training, especially if Autism characteristics are clearly present. If they do not have Autism-specific training, or if your child’s presentation is subtle or complicated by other factors, they may refer you to an Autism specialist.

Most Autism diagnosticians will not diagnose a child until they are at least one-year-old. However, if your child has delays, you can seek services before that diagnosis, often from early intervention federal programs, or from private speech, occupational therapy, or physical therapy clinics. Your primary care professional can give a referral to early intervention or private therapists.

Once your child is at least one-year-old, an Autism diagnostician (developmental pediatrician, child psychologist, child psychiatrist) can begin to explore evaluating them. The evaluation will consist of interviews with you, review of records, and an observation of or interaction with your child. See the section on Medical Diagnosis for more information.

School Age

Diagnosis for older children can follow a similar process to infants and toddlers. Contact your primary care professional for information about seeking an Autism evaluation. See the section on Medical Diagnosis for more information.

Another important area to consider for school-age children is seeking an evaluation within the school system. This process is separate from a medical diagnosis. A school evaluation can provide you and your child with federally mandated support in the school setting, via the special education system. Your child can have both a medical diagnosis of Autism and a school determination of Autism to get support in all the settings possible, including home, community, and school.

Some professionals recommend getting the medical diagnosis first, as its support will go into effect before a child enters school, and will often expedite the school determination process. However, the medical diagnosis and the school determination can be done in the order that best meets the needs of your child and your family.
The first step in obtaining special education services for a school-age child is for the child to be evaluated at school. The evaluation can be done when the child is first suspected of having a disability (pre-placement evaluation) or when the child’s disability-related needs and support changes in one or more areas (re-evaluation).

Adolescent Transition
and Adulthood

Many adults report that finding someone to diagnose them with Autism is more difficult. In some cases, diagnosticians focus only on children, especially those that would be eligible for intensive early intervention. In other cases, professionals feel less qualified to diagnose adults, as the presentation may be different, it may be complicated by life history and co-occurring mental health conditions, and professional training in diagnosing adults with Autism is more limited. As above, we recommend starting with your primary care professional. If they do not have any recommendations, consult your local Autism Society affiliate for information on specialists who may diagnose adults. Adult neuropsychologists, adult neurologists, adult psychiatrists, and adult clinical psychologists are all individuals that may be able to diagnose an adult, if they have the training

and experience. Investigate these providers’ websites or profiles to determine if Autism is an area of expertise for them. It is very important to determine that the provider has extensive experience in diagnosing adults, specifically.

An adult evaluation will consist of review of the person’s developmental history, medical and psychological history, cognitive functioning, and Autism-specific tests, such as the ADOS. One important consideration is including someone in the evaluation who can report on early developmental history of the adult, such as a parent, care-provider, sibling, or relative. This information is often more difficult to obtain for adults, but it can help speed the process.

There are two ways in which a child can be evaluated under the Individuals with Disabilities Education Act:

The parent or guardian can request an evaluation by calling or writing the director of special education or the principal of the child’s school. Note: if the child attends a private or parochial school, the parent may need to contact the local public school district for this evaluation. It is important to place an evaluation request in writing and the parents should keep a copy to help track timing of the process. Suggestions for communicating with school systems:

  • Follow up on all telephone calls with a letter summarizing the conversation to allow for correction of misunderstandings.
  • Communicate both verbally and in writing to request meetings.
  • Keep copies of evaluations performed at school.

The school system may determine that an evaluation is necessary. If so, they must receive written permission from the parent before conducting the evaluation.
An evaluation should be conducted by a multidisciplinary team or group, which must include at least one teacher or other specialist with specific knowledge in the area of the suspected disability. IDEA mandates that no single procedure can be used as the sole criterion for determining an appropriate education program. The law also requires that the child be assessed in all areas related to the suspected disability, including but not limited to health, vision, hearing, communication abilities, motor skills, and social and/or emotional status.
If the parents disagree with the results of the evaluation, they may choose to obtain an independent evaluation at public or private expense. You may request a list of professionals that meet state requirements from your school, or you can choose one on your own. If the chosen professional meets appropriate criteria set up by the state, then the school must consider their evaluation in developing an Individualized Education Plan (IEP).

School Re-Evaluation

An evaluation to consider educational Autism can be completed as part of an initial evaluation, or through the process of re-evaluation. For students who already receive special education services, a re-evaluation must take place at least every three years. It may, however, be conducted more often if the parent or a teacher makes a written request. An evaluation may also focus on a specific area of concern. A re-evaluation of all areas of suspected need is necessary if parents feel their child is not making adequate progress towards achieving their IEP goals.

Parents who feel their child’s disability category and related services and support should be changed must have a basis for requesting a re-evaluation. For example, a child may be exhibiting new skill deficits or challenging behaviors. It may be necessary to reassess their placement or develop new behavior techniques to address this area. As a first step, an evaluation by a specialist familiar with Autism-related behaviors could be requested. The IEP can then be changed to reflect the results of the evaluation.

For example, a child may have an annual goal to aim at increasing their language production and comprehension skills, but is not meeting the objectives developed in their IEP for this goal. The parent may wish to request a re-evaluation with a speech therapist who is knowledgeable about Autism. It may be determined from the results that an increase in the weekly number of hours of therapy is necessary.

A re-evaluation of all areas of suspected need may come prior to the scheduled annual IEP meeting. If the child has made significant progress since the last evaluation, the treatment, placement, and therapy recommendations may no longer be applicable. A re-evaluation addressing all areas would become the basis for a more appropriate IEP.

Parents may suggest that professionals with knowledge of Autism be present at the school for these evaluations.

The school does not have to use the suggested professional, but may appreciate the assistance in finding a qualified person. As explained above, if the parents disagree with the school’s evaluation, they do have a right to acquire an independent evaluation.

The IEP must be prepared collaboratively and agreed upon before initial placement in special education is made, rather than written after the fact to fit the special education determination.