Understanding ASD Severity Levels

  • In describing our ASD workshops and training events, we are moving away from using terms that describe children 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, underlying capacities and potential. Referring to someone as "high functioning" has been misinterpreted as indicating that the child/student does not need as much support as they truly do. 

    While it has been helpful to have terms to easily distinguish sub-types of individuals with ASD, the "low functioning" and "high functioning" terms have raised concerns that necessitated a shift in our language. 

    Since adoption of the DSM5 in 2013, workshops and training materials are increasingly using the three severity levels listed in the DSM5 diagnostic criteria for ASD. CRP has adapted the levels to assist in describing professional development opportunities. For example, rather than titling a training "Strategies for Students with High Functioning ASD" it will be titled "Strategies for Students with ASD (Level 1 Severity)".

    ASD Severity Levels 

    Greater Severity of ASD and Support Needs                        Lesser Severity of ASD and Support Needs 

     Level 3 ASD

     Level 2 ASD

    Level 1 ASD

    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



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