CARS-2 (Childhood Autism Rating Scale)
The CARS-2 (Childhood Autism Rating Scale, Second Edition) is a 15-item clinician-rated scale that quantifies autism-related behaviour in individuals aged 2 years and older, with each domain rated 1–4. Score 15–60; ≥30 autism range; ≥37 severe autism. Three forms: CARS2-ST, CARS2-HF, CARS2-QPC (WPS).
For professional reference, research, and education only. Not for diagnosis or medical advice.
CARS-2 Score Interpreter
Enter a total score to see its range.
15 subscales, each rated 1–4 (with half-point increments). Total score ranges from 15 (all within normal limits) to 60 (all severely abnormal). Higher scores indicate greater autism symptom severity.
Total score Interpretation 37+ Severe Autism RangeTotal score ≥ 37 indicates severe autism spectrum features. Full diagnostic evaluation and individualized support planning are strongly recommended. 30–36 Mild-to-Moderate Autism RangeTotal score 30–36.5 indicates mild to moderate autism spectrum features. Comprehensive clinical evaluation is warranted. 15–29 Minimal to No Symptoms (Non-Autism Range)Total score below 30 is in the non-autism range. Clinical context and developmental history should be integrated with the score. CARS-2 © Western Psychological Services (WPS). Severity ranges per Schopler E, Van Bourgondien ME, Wellman GJ, Love SR. CARS-2 Manual (2010), clinical convention. Note: optimal cut-off scores may differ by population, age, and form (ST vs. HF).
The CARS (Childhood Autism Rating Scale) is a clinician-rated scale that measures autism severity across 15 domains, with totals from 15 to 60 [1].
Totals of 30 or more fall in the autism range and 37 or more in the severe range.
What does the CARS-2 measure?
The CARS was developed by Schopler and colleagues to classify childhood autism objectively [1]. It is used to support the diagnosis of autism spectrum disorder and to quantify symptom severity across a broad age range. The current edition, CARS-2, includes three forms tailored to different clinical presentations:
- CARS2-ST (Standard), for children ages 2–6, or older children with an IQ of 79 or below, or limited verbal ability
- CARS2-HF (Verbally Fluent Form), for children age 6 and above with an IQ above 79 and some verbal ability; captures subtler features of ASD
- CARS2-QPC (Questionnaire for Parents and Caregivers), a complementary questionnaire for parents and caregivers to provide collateral information
Each of the 15 subscales is rated by the clinician on a 7-point scale (1 = within normal limits to 4 = severely abnormal), with half-point increments allowed, so the total score ranges from 15 to 60.
The CARS has shown good inter-rater and test-retest reliability [3].
The CARS-2 is proprietary and published by Western Psychological Services (WPS), and clinical administration requires appropriate training.
The CARS is not a replacement for a full diagnostic evaluation. It supports the diagnostic process and quantifies autism severity for treatment planning and outcome monitoring.
CARS-2 rating domains (15 subscales)
The CARS-2 (both ST and HF forms) rates behaviour across 15 domains. Each domain is scored 1–4 (with half-point increments), where 1 represents behaviour within normal limits for the individual's age and 4 represents severely abnormal behaviour. The domain names below follow the CARS-2 manual:
| # | Domain (CARS2-ST) |
|---|---|
| 1 | Relating to People |
| 2 | Imitation |
| 3 | Emotional Response |
| 4 | Body Use |
| 5 | Object Use |
| 6 | Adaptation to Change |
| 7 | Visual Response |
| 8 | Listening Response |
| 9 | Taste, Smell, and Touch Response and Use |
| 10 | Fear or Nervousness |
| 11 | Verbal Communication |
| 12 | Nonverbal Communication |
| 13 | Activity Level |
| 14 | Level and Consistency of Intellectual Response |
| 15 | General Impressions |
The CARS2-HF uses 15 parallel domains reworded to capture subtler manifestations appropriate for verbally fluent individuals, but preserves the same scoring structure and total score range. Factor analytic studies of the CARS-2 have found that the ST items load predominantly onto a single factor, while the HF form has shown a three-factor structure reflecting social interaction, restricted/repetitive behaviours, and sensory/emotional features [4].
How do you give the CARS-2?
The CARS-2 is clinician-administered, not self-report. The evaluating clinician rates each of the 15 domains based on:
- direct observation
- clinical interview
- developmental history
- collateral information
The CARS2-QPC parent/caregiver questionnaire can gather additional history, but the scored ST and HF forms are completed by the clinician. Clinical administration requires appropriate training, and rating typically takes 15–30 minutes.
How do you score and interpret the CARS-2?
The CARS-2 is a clinician-administered scale. Enter the total score (15–60) assigned by the evaluating clinician in the interpreter to see the corresponding severity classification.
The CARS-2 replaces the original CARS. Items are rated on a 7-point scale (1 to 4, with half-point increments), so total scores range from 15 to 60.
The CARS2-HF uses the same scoring range but is calibrated for presentations with subtler features. The standard published severity classifications are:
| Score range | Classification |
|---|---|
| 15–29.5 | Non-autism range — minimal to no autism-related features |
| 30–36.5 | Mild-to-moderate autism range |
| 37–60 | Severe autism range |
Note that optimal cut-off scores may shift depending on the population assessed, the form used (ST vs. HF), and the individual's cognitive and language profile. Research in community and cross-cultural samples has suggested that lower cut-offs (around 25–29) may better capture autism spectrum disorder across the broader diagnostic category, while the standard ≥30 threshold retains higher specificity for more pronounced presentations [2].
How does the CARS-2 compare with other autism tools?
The CARS-2 is one of several validated tools used in autism evaluation. Clinicians typically combine multiple tools to triangulate a diagnosis and build a comprehensive clinical picture. The table below summarizes how the CARS-2 compares to commonly used alternatives:
| Tool | Type | Administrator | Age range | Primary role |
|---|---|---|---|---|
| CARS-2 (ST/HF) | Clinician-rated scale | Clinician | 2+ years | Severity quantification; supports diagnosis |
| ADOS-2 | Structured observation | Trained clinician | Toddler–adult | Criterion-standard observational diagnostic assessment |
| ADI-R | Structured interview | Trained clinician | ~18 months–adult | Caregiver diagnostic interview; developmental history |
| M-CHAT-R/F | Caregiver screener | Caregiver + clinician | 16–30 months | Early population screening; not diagnostic |
| SRS-2 | Rating scale | Caregiver/teacher/self | 2.5–adult | Social responsiveness and symptom severity rating |
| SCQ | Caregiver questionnaire | Caregiver | 4+ years (MA ≥ 2 yrs) | Screening; abbreviates ADI-R domains |
The CARS-2 occupies a practical middle ground: it is faster to administer than the ADOS-2 or ADI-R (typically 15–30 minutes) and does not require the same level of intensive training, while still providing a normed severity score. It is commonly used when a full ADOS-2 is unavailable or as a complement to it.
A known limitation of the standard form is reduced sensitivity for verbally fluent individuals, a gap the CARS2-HF was designed to address. In a Korean study of 329 participants, the false-negative rate of the CARS rose from 19.8% to 36.0% when verbal IQ was above 69.5, and the authors recommended lower cut-offs for this group [5].
Psychometric properties
Most published psychometric data come from the original CARS, which shares the 15-domain, 15–60 structure:
- Diagnostic accuracy. In 2-year-old (n = 376) and 4-year-old (n = 230) children referred for possible autism, a cut-off of 25.5 distinguished ASD from non-ASD with good sensitivity and specificity at both ages, and cut-offs of 32 (age 2) and 30 (age 4) distinguished autistic disorder from PDD-NOS [2].
- Reliability. In an Indian clinical sample, inter-rater reliability (ICC = 0.74) and test-retest reliability (ICC = 0.81) were good, and internal consistency was α = 0.79; a cut-off of ≥33 gave sensitivity of 81.4% and specificity of 78.6% in that population [3].
- Factor structure. CARS-2 ST items load predominantly onto a single factor, while the HF form has shown a three-factor structure [4].
Limitations
- Not a stand-alone diagnosis. The CARS-2 supports, but does not replace, a comprehensive diagnostic evaluation.
- Cut-offs vary. Optimal thresholds differ by age, form and population (for example 25.5 for ASD versus non-ASD in young referred children, ≥33 in an Indian sample), so the standard ≥30 band should not be applied mechanically.
- Reduced sensitivity in verbally fluent individuals on the standard form; the CARS2-HF was designed to address this.
- Rater training. Scores depend on the clinician's training and on the quality of observation and collateral history.
- Licensed. The CARS-2 is proprietary and published by Western Psychological Services.
For individuals: This page is a clinical reference, not a diagnostic tool. If you have concerns about your own symptoms, bring this information to a qualified mental health professional.
Related
Billing
In the US, the CARS-2 (Childhood Autism Rating Scale) is usually billed under these CPT codes. Payer rules vary.
- Publisher
- Western Psychological Services (WPS)
- First published
- 1980
- Terms
- Clinician administration required.
Assessments
- AQ Scoring & Cutoffs · Autism Spectrum Quotient
- Autism Spectrum Quotient, Brief (AQ-10)
- CAST: Childhood Autism Spectrum Test
- Epworth Sleepiness Scale (ESS)
- ISI: Insomnia Severity Index
- PSQI: Pittsburgh Sleep Quality Index
Dot size shows how strongly each scale's condition is linked to this one in HiBoop's co-occurrence map.
FAQ
What does a CARS-2 score mean?
The CARS-2 produces a total score from 15 to 60. Scores below 30 fall in the non-autism range. Scores from 30 to 36.5 suggest mild-to-moderate autism spectrum features. Scores of 37 or above suggest severe autism spectrum features. The score should always be interpreted in the context of a full clinical evaluation, not in isolation.
Is the CARS-2 self-report or clinician-administered?
The CARS-2 is clinician-administered, not self-report. The evaluating clinician rates each of the 15 domains based on direct observation, clinical interview, developmental history, and collateral information. A complementary parent/caregiver questionnaire (CARS2-QPC) can be used to gather additional history, but the scored forms are completed by the clinician.
Can the CARS-2 diagnose autism spectrum disorder?
No single scale can diagnose autism spectrum disorder on its own. The CARS-2 is a validated tool that supports the diagnostic process by quantifying symptom severity across 15 domains, but a formal ASD diagnosis requires a comprehensive clinical evaluation integrating developmental history, direct observation, and multiple sources of information.
What is the difference between CARS2-ST and CARS2-HF?
The CARS2-ST (Standard Form) is used for children aged 2 years and older who have an IQ at or below 79 or limited verbal ability. The CARS2-HF (Verbally Fluent Form) is designed for individuals aged 6 and above with an IQ above 79 and meaningful verbal ability; it captures subtler features that may be missed on the standard form. Both forms share the same 15-to-60 scoring range.
References
- 1.Schopler E, Reichler RJ, DeVellis RF, Daly K. Toward objective classification of childhood autism: Childhood Autism Rating Scale (CARS). J Autism Dev Disord. 1980;10(1):91-103.
- 2.Chlebowski C, Green JA, Barton ML, Fein D. Using the childhood autism rating scale to diagnose autism spectrum disorders. J Autism Dev Disord. 2010;40(7):787-99.
- 3.Russell PS, Daniel A, Russell S, Mammen P, Abel JS, Raj LE, Shankar SR, Thomas N. Diagnostic accuracy, reliability and validity of Childhood Autism Rating Scale in India. World J Pediatr. 2010;6(2):141-7.
- 4.Samadi SA, Mahmoodizadeh A, Foladgar M, Moradi SB, Lotfi B, McConkey R. The Childhood Autism Rating Scale Second Edition (CARS2) and Its Applicability in an Iranian Sample. Autism Res. 2025;18(3):541-552.
- 5.Kwon HJ, Yoo HJ, Kim JH, et al. Re-adjusting the cut-off score of the Korean version of the Childhood Autism Rating Scale for high-functioning individuals with autism spectrum disorder. Psychiatry Clin Neurosci. 2017;71(10):725-732.
CARS-2 © Western Psychological Services (WPS). Clinician administration required.
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