Autism tests › CAST
The CAST: screening the primary-school years
Between the toddler screens and the adult questionnaires sits an age group that is easy to overlook — children who sailed through their early milestones and only became visibly different once school demanded friendships, flexibility, and unwritten social rules. The CAST was built for exactly them.
| Type | Screening questionnaire (not diagnostic) |
|---|---|
| Age range | 4–11 years, children in mainstream education |
| Format | 39 yes/no questions answered by a parent, carer or teacher — 31 of them scored, giving a range of 0–31; about 10 minutes |
| Origin | Scott, Baron-Cohen, Bolton & Brayne, University of Cambridge — originally the "Childhood Asperger Syndrome Test," renamed after the 2013 diagnostic changes |
| Cutoff | A score of 15 or above is the published threshold for considering further assessment (at that cut-point the validation study reported 100% sensitivity and 97% specificity, with a positive predictive value of 50%) |
| Cost | Free for clinical and research use from the Cambridge Autism Research Centre |
What it asks about
The questions cover the everyday texture of a school-age child's social life: how they play with other children, whether friendships form and last, how they handle conversation and turn-taking, whether routines and interests are unusually rigid or intense, how they cope with change, and how literally they take language. Because it was written for children in mainstream classrooms, it assumes a child with functional language — this is not the right instrument for a child with significant language or intellectual delay, where the SCQ or a direct referral fits better.
Where it fits
The CAST fills a real gap on this site's map. The M-CHAT-R/F stops at 30 months; the AQ and RAADS-R begin in adulthood. For the years in between, the practical options are the SCQ, the SRS-2, and the CAST — with the CAST's advantages being that it's free, brief, and written specifically for the mainstream-school population where late identification is most common.
The pattern the CAST is good at catching. A child whose early development looked unremarkable, who is doing fine or well academically, but for whom the social side of school is quietly exhausting — few durable friendships, meltdowns that arrive at home rather than in class, intense interests, real distress when plans change. This profile is disproportionately common in autistic girls, and it is the profile most often explained away as shyness, anxiety, or being "a bit quirky" for years.
What a score does and doesn't mean
The usual rule of this site applies without modification: at or above the cutoff means a full assessment is worth arranging — nothing more. Below it does not rule autism out, and the CAST is a screening instrument validated for identifying children who warrant assessment, not a measure of how autistic anyone is. A child who masks well at school can be rated by a parent who only sees the aftermath, or by a teacher who only sees the mask, and get two very different scores. Both are information; neither is a verdict.
After the CAST
An elevated score points toward a comprehensive evaluation — typically an ADOS-2 plus a developmental history such as the ADI-R, judged against the diagnostic criteria. For school-age children in the U.S., request a school evaluation in writing at the same time; educational eligibility runs on its own track alongside any clinical diagnosis. See next steps.
Medical disclaimer: Educational information only. The CAST belongs to its authors at the University of Cambridge; no questionnaire items are reproduced here. This page cannot diagnose your child; consult a qualified clinician.