CARS-2 (Childhood Autism Rating Scale)

The CARS (Childhood Autism Rating Scale) is a clinician-administered assessment scale measuring autism severity across 15 domains. Score 15–60; ≥30 autism range; ≥37 severe. One of the most widely used autism assessment tools worldwide. Schopler et al. (1988).

What is the Childhood Autism Rating Scale?

The CARS (Childhood Autism Rating Scale) is a standardized clinician-administered assessment tool developed by Schopler, Reichler, and Renner (1988) to diagnose autism spectrum disorder and 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. The total score ranges from 15 to 60. Scores below 30 fall in the non-autism range; 30–36.5 indicate mild to moderate autism; 37 or above indicate severe autism. The CARS has demonstrated strong inter-rater reliability and criterion validity against established DSM and ICD diagnostic criteria.

The CARS-2 is proprietary and published by Western Psychological Services (WPS). Clinical administration requires appropriate training. It is widely used in diagnostic clinics, schools, early intervention programs, and research settings worldwide. The CARS is not a replacement for full diagnostic evaluation but is a validated tool to support the diagnostic process and quantify autism severity for treatment planning and outcome monitoring.

CARS-2 Score Interpreter

The CARS-2 is a clinician-administered scale. Enter the total score (15–60) assigned by the evaluating clinician to see the corresponding severity classification.

Educational reference only. CARS-2 is © Western Psychological Services, clinician administration required. This tool does not substitute for a full autism diagnostic evaluation.

CARS-2 Score Interpretation

The CARS-2 (Schopler, Van Bourgondien, Wellman & Love, 2010) replaces the original CARS (1988). 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:

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 (Chlebowski et al., 2010).

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 (Schopler et al., 2010):

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 (Samadi et al., 2025).

CARS-2 vs. Other Autism Assessment Tools

The CARS-2 is one of several validated instruments 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:

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. Research has shown that the standard CARS false-negative rate increases substantially for individuals with higher verbal and adaptive abilities (Kwon et al., 2017, noting that cut-off thresholds benefit from downward adjustment in these cases).

Neurodevelopmental Outcome Tracking in HiBoop

CARS-2 alongside Vanderbilt ADHD, ASRS, SCARED, and PHQ-A, automated scoring and longitudinal outcome tracking for autism, ADHD, and neurodevelopmental conditions across your patient panel.