The autism diagnostic criteria, in plain language
Every screening questionnaire and every diagnostic instrument on this site ultimately serves one purpose: helping a clinician decide whether a person meets these criteria. Here is what they actually say — paraphrased in everyday language, with the parts that are most often misread flagged.
Two manuals, one condition. In the United States, clinicians diagnose against the DSM-5-TR (American Psychiatric Association, 2022 text revision). Most of the rest of the world uses the World Health Organization's ICD-11 (in effect since 2022). They describe the same condition and agree closely; the differences are in structure, not substance.
DSM-5-TR: five criteria, A through E
A diagnosis requires all five. Criteria A and B describe the two core domains; C, D, and E are the qualifying conditions that separate autism from other explanations.
Differences in social communication and social interaction
Persistent, across multiple contexts — not just at school or just with strangers. All three areas must be present, currently or historically:
- Social-emotional reciprocity — the back-and-forth of interaction: sharing interests and emotions, initiating or responding to social approaches, the natural rhythm of conversation.
- Nonverbal communication used socially — how eye contact, gesture, facial expression, body language, and speech fit together (or don't) in the service of connecting.
- Developing, maintaining, and understanding relationships — adjusting behavior to different social situations, shared imaginative play, making and keeping friendships, interest in peers.
Restricted, repetitive patterns of behavior, interests, or activities
At least two of these four, currently or historically:
- Repetitive movements, use of objects, or speech — hand flapping, lining up toys, echoed phrases, idiosyncratic language.
- Insistence on sameness — inflexible routines, ritualized patterns, distress at small changes, needing the same route or the same words.
- Highly restricted, fixated interests — unusual in their intensity or their focus.
- Sensory differences — over- or under-reacting to sounds, textures, light, pain or temperature; or unusual sensory fascination. Note that this one was only added in 2013; before that, sensory experience wasn't part of the official picture at all, which is one reason many adults were missed.
The three qualifying conditions
- C — Present in the early developmental period. Crucially, the manual adds that traits may not become fully apparent until social demands exceed a person's capacity, or may be masked by learned strategies later in life. This sentence is why adults and women diagnosed at 30 or 50 are not exceptions to the rule — they are explicitly accounted for by it.
- D — Causing meaningful impairment in social, occupational, or other important areas of current functioning. This is what instruments like the Vineland-3 measure rather than assume.
- E — Not better explained by intellectual disability or global developmental delay. These frequently co-occur with autism; the criterion only requires that social communication be below what the person's overall development would predict.
The severity levels — the most misunderstood part
DSM-5-TR asks clinicians to rate support needs on three levels, separately for social communication and for restricted/repetitive behaviors:
| Level | Wording | What it describes |
|---|---|---|
| Level 1 | "Requiring support" | Difficulties are apparent and cause real problems without support in place |
| Level 2 | "Requiring substantial support" | Marked difficulties apparent even with supports in place |
| Level 3 | "Requiring very substantial support" | Severe difficulties, very limited initiation, major impact on functioning |
Three things people routinely get wrong about these levels:
- They are not severity of autism — they are severity of support needed. The label describes a relationship between a person and their environment, not a quantity of autism inside them.
- They are not stable. They describe the current picture, in the current setting. A child can be rated differently at 4, at 9, and at 15, and a person can be "Level 1" at home and functionally Level 2 in a loud classroom.
- A person can be split across levels — Level 1 social communication and Level 2 restricted/repetitive behaviors is a perfectly ordinary result, which is exactly why they are rated separately.
You will also see specifiers in a report: with or without accompanying intellectual impairment, with or without accompanying language impairment, associated with a known genetic or medical condition, associated with another neurodevelopmental or mental health condition, and with catatonia.
ICD-11: the same condition, organized differently
ICD-11 lists autism spectrum disorder under code 6A02, describing the same two core domains: persistent differences in social interaction and social communication, together with restricted, repetitive, inflexible patterns of behavior and interests. Onset is in the developmental period, with the same acknowledgment that difficulties may only become obvious when demands increase.
The structural difference is that ICD-11 builds its subcategories directly into the diagnosis, combining two dimensions: whether there is an accompanying disorder of intellectual development, and the degree of functional language impairment. So an ICD-11 diagnosis reads as something like "autism spectrum disorder without disorder of intellectual development and with mild or no impairment of functional language" — descriptive by design, rather than adding severity levels on top.
What changed in 2013 — and why it still confuses people
Before DSM-5 (2013), what is now one diagnosis was four separate ones: autistic disorder, Asperger's disorder, childhood disintegrative disorder, and PDD-NOS. They were merged into a single autism spectrum disorder, because the research did not support drawing reliable boundaries between them — the same child could receive different labels from different clinics.
Two consequences you'll meet in real life:
- "Asperger's" is no longer a diagnosis in either manual, but many people diagnosed before 2013 still use it as an identity, and that is entirely their right. Clinically, they meet criteria for autism spectrum disorder.
- Social (Pragmatic) Communication Disorder was introduced in the same revision for people who have the social communication differences of criterion A without the restricted and repetitive patterns of criterion B. If your child's report mentions it, this is what it means.
A word about the language. These criteria are written in the vocabulary of deficits and impairments, because they are a clinical classification tool designed to establish medical need — which is also what unlocks services. They are not a description of who your child is, what they will become, or what they're worth. Plenty of what appears above as a "restricted interest" is, from the inside, simply what someone loves. Hold both: the criteria as a key to support, and your child as a whole person.
How this connects to everything else
Screening questionnaires like the M-CHAT-R/F ask about behaviors that predict these criteria. Diagnostic instruments like the ADOS-2 and ADI-R gather the structured observation and history a clinician needs to judge them. Nothing on this page is a checklist you can score yourself — the judgment of whether a pattern rises to "persistent," "meaningful impairment," or "not better explained by" is precisely the clinical expertise being paid for. See how the pathway works, or start with the signs by age.
Sources
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). Washington, DC: APA Publishing, 2022 — autism spectrum disorder, 299.00 (F84.0). Criteria paraphrased here in plain language; the manual's own wording is copyrighted. psychiatry.org/dsm
- World Health Organization. ICD-11 for Mortality and Morbidity Statistics — 6A02 Autism spectrum disorder. icd.who.int
- CDC. Diagnostic Criteria for Autism Spectrum Disorder. cdc.gov/autism/hcp/diagnosis
- Hyman SL, Levy SE, Myers SM; AAP Council on Children with Disabilities. Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. Pediatrics 2020;145(1). publications.aap.org
Medical disclaimer: Educational information only. This page paraphrases published diagnostic criteria for general understanding; it is not the diagnostic manual, not a checklist, and not a substitute for evaluation by a qualified clinician.