CAST: Childhood Autism Spectrum Test
The CAST (Childhood Autism Spectrum Test) is a 37-item parent-report screening questionnaire for autism spectrum characteristics in children aged 4–11, designed for community and school settings. Scored 0–31; a score ≥15 indicates further evaluation is warranted.
CAST Score Interpreter
Meets the ≥15 screening threshold; a full diagnostic evaluation by a qualified clinician is warranted. Half of positive screens in the validation study did not have a consensus diagnosis.
37 yes/no parent-report items; 31 are scored 0 or 1 (6 are unscored), giving a total of 0–31. Higher scores reflect more autism spectrum characteristics.
| Total score | Interpretation |
|---|---|
| 15+ | Positive screenMeets the ≥15 screening threshold; a full diagnostic evaluation by a qualified clinician is warranted. Half of positive screens in the validation study did not have a consensus diagnosis. |
| 0–14 | Below thresholdBelow the screening threshold. A score under 15 does not rule out an autism spectrum condition; clinical judgement is required if concern remains. |
Williams J et al. Autism. 2005;9(1):45-68 (PMID 15618262): at the cut-point of 15, sensitivity 100%, specificity 97%, positive predictive value 50% in 1,925 children aged 5–11 in mainstream schools. Educational reference only — not a diagnostic tool.
For reference only — not an assessment, diagnosis, or medical advice. This page provides scoring reference material; interpretation and clinical decisions rest with a qualified clinician.
About the CAST
The Childhood Autism Spectrum Test (CAST), originally called the Childhood Asperger Syndrome Test, was developed at the Autism Research Centre, University of Cambridge. It is a parent-completed questionnaire intended for use in community and school settings to identify children who may have autism spectrum characteristics.
The CAST was developed in response to the underidentification of autism in children who do not present with significant intellectual disability. It aims to capture the broader autism phenotype, including children whose social and communicative differences are subtle enough to go unrecognized in standard developmental checks.
The tool covers a broad range of behaviors across social communication, play, and routine domains, drawing on DSM and ICD criteria relevant to autism spectrum conditions.
What the CAST measures
The CAST evaluates autism-related characteristics across:
- Social and peer interactions, difficulty initiating or maintaining friendships, reduced interest in other children
- Communication, unusual language use, difficulty with conversational reciprocity
- Play and imagination, preference for solitary, repetitive, or rule-bound activities
- Routines and flexibility, insistence on sameness, distress at change
- Motor and sensory features, unusual sensory responses, motor stereotypies
How to administer the CAST
A parent or primary caregiver completes the CAST on behalf of the child; no clinician administration or specialized training is required for completion, though interpretation and any follow-up assessment should involve a qualified professional.
- Ages: 4–11 years
- Respondent: Parent or primary caregiver
- Items: 37 yes/no questions
- Administration time: Approximately 10 minutes
- Setting: Community, school, or clinical screening
CAST scoring and interpretation
The CAST yields a total score (range 0–31 scoreable items; 6 items are not scored).
Recommended cutoff (Scott et al., 2002):
- Score ≥15: Meets the screening threshold; warrants full diagnostic evaluation
- Score <15: Does not rule out autism spectrum conditions; clinical judgment is required
The CAST is intended as a screening tool only and does not provide a diagnosis. A positive screen should prompt a referral for comprehensive assessment.
Psychometric properties
The CAST has been validated across multiple languages and cultural contexts:
- Test accuracy (UK). In 1,925 children aged 5–11 in mainstream Cambridgeshire schools, with diagnostic assessment conducted blind to screen status, sensitivity at the cut-point of 15 was 100%, specificity 97% and positive predictive value 50%; accuracy varied with the case definition used (Williams et al., 2005)
- Spanish version. In 4–12-year-olds from community and clinical settings, a cut-off of 15 gave sensitivity of 83.9%, specificity of 92.5% and internal consistency α = .826 (Morales-Hidalgo et al., 2017)
- Mandarin version. Test-retest reliability at the cut-off of 15 was good (kappa = 0.64) over 2–4 months (Sun et al., 2013); in Beijing primary schools, the UK cutoff gave 84% sensitivity and 96% specificity (Sun et al., 2015)
Limitations
- The CAST identifies children across the full autism spectrum, not only those with intellectual disability or classic autistic presentations
- Girls and children who mask autistic traits may score below the cutoff despite meeting diagnostic criteria; the CAST should be interpreted alongside direct observation and developmental history
- A negative screen does not preclude further evaluation if clinical concern remains
- Screening, not diagnosis: half of positive screens in the UK validation study did not receive a consensus diagnosis (PPV 50%)
- Williams et al. (2005) concluded there was not yet enough evidence to recommend the CAST within a public health screening programme in the general population; it is best suited to clinical, school and research screening
- Parent report depends on the parent's observations and may differ from teacher or clinician views
Who the CAST Is For
The CAST is appropriate when:
- A parent, teacher, or clinician has concerns about a child aged 4–11
- The clinical question involves autism spectrum characteristics, social communication difficulties, or restricted/repetitive behaviors
- School-based or research autism screening is being conducted
This library is an academic and clinical reference. A scale described here is not necessarily offered in HiBoop; each page says whether it is.
Frequently Asked Questions
How is the CAST scored?
The CAST contains 37 yes/no questions, of which 31 contribute to the total score (6 items are unscored). Each scored item counts as 0 or 1, giving a possible range of 0–31. Scoring is completed by the parent or caregiver and takes only a few minutes once the questionnaire is finished.
What does a CAST score of 15 or above mean?
A score of 15 or above meets the recommended screening threshold and indicates that a full diagnostic evaluation by a qualified clinician is warranted. Williams et al. (2005) reported 100% sensitivity and 97% specificity at this cut-point in a population-based UK sample. Reaching the threshold does not constitute a diagnosis of an autism spectrum condition.
Is the CAST self-report or clinician-administered?
The CAST is a parent-report questionnaire: a parent or primary caregiver completes it on behalf of the child. No clinician administration or specialized training is required for completion, though interpretation and any follow-up assessment should involve a qualified professional.
Can the CAST diagnose autism in a child?
No. The CAST is a screening tool designed to identify children who may benefit from further evaluation, not to provide a diagnosis. A positive screen should prompt referral for a comprehensive multidisciplinary assessment using validated diagnostic tools such as the ADOS-2 or ADI-R.
Bill this assessment
In the US, the CAST: Childhood Autism Spectrum Test is usually billed under these CPT codes. Payer rules vary.
Using this assessment in practice
For clinicians
Send it as a gentle check-in before the session. The score is waiting when you open the chart, and the trend builds itself.
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.
References
- 1.Scott FJ, Baron-Cohen S, Bolton P, Brayne C. The CAST (Childhood Asperger Syndrome Test): preliminary development of a UK screen for mainstream primary-school-age children. Autism. 2002;6(1):9-31.View source
- 2.Williams J, Scott F, Stott C, Allison C, Bolton P, Baron-Cohen S, Brayne C. The CAST (Childhood Asperger Syndrome Test): test accuracy. Autism. 2005;9(1):45-68.View source
- 3.Morales-Hidalgo P, Roigé-Castellví J, Vigil-Colet A, Canals Sans J. The Childhood Autism Spectrum Test (CAST): Spanish adaptation and validation. Autism Res. 2017;10(9):1491-1498.View source
- 4.Sun X, Allison C, Auyeung B, Matthews FE, Baron-Cohen S, Brayne C. The Mandarin Chinese version of the childhood autism spectrum test (CAST): test-retest reliability. Res Dev Disabil. 2013;34(10):3267-75.View source
- 5.Sun X, Allison C, Matthews FE, et al. Exploring the Underdiagnosis and Prevalence of Autism Spectrum Conditions in Beijing. Autism Res. 2015;8(3):250-60.View source
Last reviewed: Jun 3, 2026
Related Assessments
Explore complementary clinical tools and screeners