Interactive Interpreter

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.

For professional reference, research, and education only. Not for diagnosis or medical advice.

CAST Score Interpreter

  • Enter a total score to see its range.

  • 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 scoreInterpretation
    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.
    0–14Below 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.

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 [1].

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 behaviours across social communication, play, and routine domains, drawing on DSM and ICD criteria relevant to autism spectrum conditions.

What does the CAST measure?

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 do you give 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

How do you score and interpret the CAST?

The CAST yields a total score (range 0–31 scoreable items; 6 items are not scored).

Recommended cutoff [2]:

  • 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 [2]
  • 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 [3]
  • Mandarin version. Test-retest reliability at the cut-off of 15 was good (kappa = 0.64) over 2–4 months [4]; in Beijing primary schools, the UK cutoff gave 84% sensitivity and 96% specificity [5]

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%) [2]
  • The validation study authors concluded there was not yet enough evidence to recommend the CAST within a public health screening programme in the general population [2]; 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 behaviours
  • School-based or research autism screening is being conducted

Related autism measures include the SRS, AQ-10 and RAADS-R.

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

FAQ

  • 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. In the UK validation study, it had 100% sensitivity and 97% specificity at this cut-point in children from mainstream primary schools. 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.

References

    1. 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.
    2. 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.
    3. 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.
    4. 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.
    5. 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.

    © Autism Research Centre, University of Cambridge. Free for research and non-commercial clinical use with acknowledgement of ARC; commercial use requires permission through Cambridge Enterprise.

This library is an academic and clinical reference. A scale described here is not necessarily offered in HiBoop; each page says whether it is.

Add to your practice