Understanding Autism Severity Levels

  • In describing our autism workshops and training events and in our day-to-day communication regarding children and youth, we do not use functioning labels; terms that describe individuals as "high" or "low" functioning. These terms are problematic for a number of reasons. Referring to someone as "low functioning" can result in an underestimation of the child's strengths and capacities. We presume the potential of every child and youth to learn and grow when provided with developmentally appropriate, empirically supported intervention delivered in a neurodiversity-affirming manner by well-trained teachers and therapists. Referring to an individual as "high functioning" has been interpreted as indicating that they have a "mild" form of autism, suggesting little or no need for specialized services and support.  

    The autism spectrum is characterized by remarkable heterogeneity and we recognize the utility of terminology to concisely distinguish between individuals on different ends of the spectrum. We embrace language that emphasized level of support need versus severity of impairment. The DSM-5 published in 2013 created a broad category of autism spectrum disorder (ASD) with three severity levels based on degree and type of support needs. Organizations have been increasingly using these severity levels in training materials and publications. At CRIS, we have adapted the levels to assist in describing our professional development opportunities. For example, rather than titling a training "Classroom Strategies for Students with High Functioning Autism" this event would be titled "Classroom Strategies for Autistic Students (Level 1)".

    Autism Severity Levels 

    More intensive support needs                     Less intensive support needs

     Level 3 Autism

     Level 2 Autism

    Level 1 Autism

    Severe deficits in verbal and nonverbal social communication skills cause severe impairments in functioning, very limited initiation of social interactions, and minimal response to social overtures from others.

    For example, a person with few words of intelligible speech who rarely initiates interaction and, when he or she does, makes unusual approaches to meet needs only and responds to only very direct social approaches

    Inflexibility of behavior, extreme difficulty coping with change, or other restricted/repetitive behaviors markedly interfere with functioning in all spheres. Great distress/difficulty changing focus or action.


    Marked deficits in verbal and nonverbal social communication skills; social impairments apparent even with supports in place; limited initiation of social interactions; and reduced or  abnormal responses to social overtures from others.

    For example, a person who speaks simple sentences, whose interaction is limited  to narrow special interests, and who has markedly odd nonverbal communication.

    Inflexibility of behavior, difficulty coping with change, or other restricted and repetitive behaviors appear frequently enough to be obvious to the casual observer and interfere with functioning in a variety of contexts. Distress and/or difficulty changing focus or action.


    Without supports in place, deficits in social communication cause noticeable impairments. Difficulty initiating social interactions, and clear examples of atypical or unsuccessful response to social overtures of others. May appear to have decreased interest in social interactions.

    For example, a person who is able to speak in full sentences and engages in communication but whose to- and-fro conversation with others fails, and whose attempts to make friends are odd and typically unsuccessful.

    Inflexibility of behavior causes significant interference with functioning in one or more contexts. Difficulty switching between activities. Problems of organization and planning hamper independence



    Return to the main ASD Training page.