Understanding the Three Levels of Autism

There are three levels of autism spectrum disorder (ASD), which are described in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5).

Each person with ASD is further diagnosed with either ASD level 1, level 2, or level 3, depending on how severe their disorder is and how much support they need in their daily life.

The levels range from least to most severe, with ASD level 3 describing an individual who has the most severe level of ASD symptoms, and ASD level 1 describing someone with symptoms on the milder end of the spectrum.

This article discusses the symptoms that are typical of each of the three ASD levels. It also includes realistic examples of the strengths and limitations that are unique to each level.

3 functional levels of autism

Verywell / Cindy Chung

Autism Spectrum Levels

Autism spectrum disorder affects how a person acts, learns, and expresses themselves. While individuals with ASD can share symptoms in common, each individual is different and so are their strengths and difficulties.

The three levels of ASD help doctors prescribe appropriate therapies for the unique needs of their patients. These therapies can help the person with ASD make the most of their strengths and improve their social, language, and behavior skills.

For parents of a child with ASD, knowing which level the child has can help prepare them for the types of challenges their child might face in daily life.

The previous version of the DSM, the DSM-4, divided autism into five distinct diagnoses ranging from Asperger's syndrome (often used to describe mild or high-functioning autism) to autistic disorder, which indicated severe autism.

The DSM-5 combines all of these into the single diagnosis of ASD, but with different levels of severity.

Level 1: Requires Support

Level 1 ASD is the mildest form of autism. Children with level 1 ASD have a hard time communicating appropriately with others. For example, they may not say the right thing at the right time or be able to read social cues and body language.

A person with ASD level 1 usually is able to speak in full sentences and communicate, but has trouble engaging in back-and-forth conversation with others. They may try to make friends, but not be very successful.

They may also have trouble moving from one activity to another or trying new things. Additionally, they may have problems with organization and planning, which may prevent them from being as independent as other people their age.

Level 2: Requires Substantial Support

People with ASD level 2 will have more obvious problems with verbal and social communication than those diagnosed with level 1. Likewise, they will find it harder to change focus or move from one activity to the next.

Children with level 2 tend to have very narrow interests and engage in repetitive behaviors that can make it difficult for them to function in certain situations. For example, they may pace back and forth or say the same thing over and over again.

A person diagnosed with ASD level 2 tends to speak in simple sentences and also struggles with nonverbal forms of communication.

Level 3: Requires Very Substantial Support

Level 3 is the most severe form of autism. Children in this category will have many of the same behaviors as those with levels 1 and 2, but to a more extreme degree.

Problems expressing themselves both verbally and nonverbally can make it very hard to function, interact socially, and deal with a change in focus or location. Engaging in repetitive behaviors is another symptom of level 3 ASD.

A person with ASD level 3 will have a very limited ability to speak clearly and will rarely start interactions with other people. When they do, they will do so awkwardly. Someone with level 3 will also respond only to very direct social approaches from other people.

Limitations of ASD Levels

Although the ASD levels are useful for diagnosing autism severity and support needs, the categories don't give a full picture of the strengths and limitations of each level.

The three levels are not entirely inclusive of the symptoms and needs of all people with autism. The DSM-5 offers little specificity regarding the types of support that individuals need or situations when support is needed.

For example, some people with ASD need support at school but are fine at home, while others may do well at school but struggle in social situations.

What's more, the level a person is assigned when they're first diagnosed can shift as they develop and refine their social skills, and as anxiety, depression, or other issues common among people with autism change or grow more severe.

Assigning people to one of the three levels of autism can be useful for understanding what types of services and supports would serve them best.

It won't, however, predict or account for unique details in their personality and behavior, which means the support and services they receive will need to be highly individualized.


The DSM-5 is an important manual used by doctors to diagnose people with autism spectrum disorder. It describes three levels of ASD, which range in severity and how much support the person with ASD needs in daily life.

The three ASD levels give a basic outline of the challenges someone with ASD may face with communicating, socializing, and behaving. This way of diagnosing people with ASD does not, however, fully address the diverse array of needs people with autism have.

Frequently Asked Questions

  • What are the different levels of autism?

    An autism spectrum disorder diagnosis is broken into levels 1, 2, and 3. These levels indicate the extent to which autism impacts an individual's ability to communicate and take care of themselves. The levels describe the disorder's severity and how much support a person needs. 

  • What is the most severe level of autism?

    Level 3 is the most severe level of autism. People with level 3 autism have limited ability to speak clearly. Difficulty with both verbal and nonverbal communication makes it challenging to interact with others. This level of autism requires a higher level of support throughout life.

  • Do children with level 1 autism need a classroom aide?

    Possibly, though each person with autism is different. Level 1 autism is the mildest form of autism, but it is still defined as needing support.

    Some people with level 1 autism have difficulty in a mainstream classroom due to sensory challenges and are more comfortable in a smaller class setting. Others may be comfortable in a typical classroom without an aide, while some may need a one-on-one or shared aide to help keep them on track.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Autism Spectrum Disorder Diagnostic Criteria.

  2. Weitlauf AS, Gotham KO, Vehorn AC, et al. Brief report: DSM-5 "levels of support:" A comment on discrepant conceptualizations of severity in ASD. J Autism Dev Disord. 2014;44(2):471-6. doi:10.1007/s10803-013-1882-z

  3. Masi A, Demayo MM, Glozier N, et al. An overview of autism spectrum disorder, heterogeneity and treatment options. Neurosci Bull. 2017;33(2):183-193. doi:10.1007/s12264-017-0100-y

By Lisa Jo Rudy
Lisa Jo Rudy, MDiv, is a writer, advocate, author, and consultant specializing in the field of autism.