ADOS-2 Autism Test: What It Is and What to Expect

The ADOS-2 autism test (Autism Diagnostic Observation Schedule, Second Edition) is a structured play-and-conversation session in which a trained clinician observes social communication, play, and repetitive behaviors. It takes about 40 to 60 minutes, has five modules for different ages and language levels, and supports a diagnosis rather than making one on its own [1][2].

What is the ADOS-2 autism test?

The original ADOS was published in 2000 as a standardized, semi-structured assessment of social interaction, communication, play, and imaginative use of materials [3]. A toddler module was later developed for children under 30 months [4], and the second edition (ADOS-2) was published in 2012 by Catherine Lord and colleagues [1].

The ADOS-2 creates natural chances for social communication. The clinician might blow bubbles, start a pretend birthday party, look at a picture book together, or have a conversation, and then notes how your child responds, shares, asks, and plays. The AAP describes it as a tool designed to draw out social language and behaviors, which requires intensive training to give and score accurately [2].

It is widely used. In the CDC’s 2022 surveillance data, the ADOS was the most commonly documented autism test among autistic eight-year-olds [5].

ADOS-2 modules: which one will my child get?

The clinician chooses one module based on your child’s age and expressive language [1]:

• Toddler Module: for children aged 12 to 30 months who do not consistently use phrase speech. It gives “ranges of concern” rather than a cutoff score [4].
• Module 1: for children 31 months and older with the most limited spoken language.
• Module 2: for children of any age who use phrase speech but are not verbally fluent.
• Module 3: for verbally fluent children and young adolescents.
• Module 4: for verbally fluent older adolescents and adults.

The publisher lists administration time as 40 to 60 minutes [1], while the AAP describes 30 to 45 minutes [2]. Scoring takes extra time afterward.

What happens during the ADOS-2 autism test

• Where: usually a clinic room with a table, toys, and books.
• Who: one or two trained clinicians. For toddlers and Module 1, a parent usually stays and may be asked to join in some activities.
• What: a series of short activities, such as free play, responding to name, bubble play, snack time, pretend play, looking at books, and, for older children, conversation and questions about friendships and feelings.
• Afterward: the clinician codes what they saw and calculates scores using the module’s algorithm.

Many children enjoy it because it feels like play. If your child is upset, tired, or unwell, tell the clinician. It may be better to reschedule.

How accurate is the ADOS-2?

A Cochrane review of autism diagnostic tools in preschool children found the ADOS was the most sensitive of the tools studied. Its summary sensitivity was 94% (correctly identifying most autistic children) and its specificity was 80% (correctly identifying most non-autistic children), but results varied a lot and performance was lower in studies with a lower risk of bias [6]. A later meta-analysis estimated ADOS-2 sensitivity at about 89% to 92% and specificity at 81% to 85%, and found evidence from real-world clinics was less robust than from research settings [7].

In practice, this means a high score is strong evidence but not proof, and a low score does not rule autism out, especially in children who mask, are older, or have other conditions. That is why NICE advises clinicians not to rely on any autism-specific diagnostic tool alone [8].

Limits of the ADOS-2 autism test

The ADOS-2 autism test is a snapshot of one session in one setting. The Cochrane authors note that in groups where autism is less common, the risk of wrongly identifying children who are not autistic would be higher [6]. Children with other conditions, such as intellectual disability, language disorder, ADHD, or anxiety, may score in ways that are hard to interpret, which is why clinicians also assess language, learning, and other conditions [2][8]. A skilled clinician weighs all of this rather than relying on the score alone.

ADI-R and other autism assessment tools

ADI-R (Autism Diagnostic Interview-Revised)

The ADI-R is a semi-structured interview with a parent or caregiver about the child’s development and behavior. It was designed for people with a mental age from about 18 months into adulthood [9]. The AAP describes it as lengthy and mainly used in some clinical and research settings [2]. In the Cochrane review, the ADI-R was less sensitive than the ADOS, and combining the two did not improve on the ADOS alone in the one study that tested this [6].

CARS-2 (Childhood Autism Rating Scale, Second Edition)

A clinician completes a 15-item scale based on history and observation [2]. The Cochrane review found CARS had a summary sensitivity of 80% and specificity of 88% [6].

Questionnaires

Questionnaires such as the Social Communication Questionnaire (SCQ) and Social Responsiveness Scale (SRS) give structured information about autistic traits, but the AAP says none is sufficient alone to make a diagnosis [2].

Telehealth tools

Tools such as the TELE-ASD-PEDS let clinicians coach parents through play activities by video. In a trial of 144 toddlers, video assessment agreed with later in-person assessment, including the ADOS-2, for 92% of children [10].

How to prepare your child for the ADOS-2 autism test

You do not need to do much to prepare for the ADOS-2 autism test, but a few steps can help your child feel at ease.

• Keep it simple. Tell your child they are going to play and talk with someone new. You might show a picture of the building.
• Do not practice or coach. The clinician needs to see your child’s usual behavior.
• Plan for comfort. Choose a time of day when your child is usually rested, and bring snacks, drinks, and a comfort item.
• Share context. Tell the clinician about sensory sensitivities, recent illness, or anything unusual about the day.
• Bring your observations. Videos and notes help balance a single snapshot. See what happens at an autism assessment.

When to talk to a professional

If you are told your child “passed” or “failed” the ADOS-2 autism test without a wider discussion, ask how the result fits with the history, other testing, and diagnostic criteria. If you disagree with the conclusion, ask the team to explain their reasoning or request a second opinion [11]. For help preparing, see our list of questions to ask at an autism assessment.

Frequently asked questions

Can my child fail the ADOS-2?

No. The ADOS-2 is not a pass-or-fail test, and your child cannot do it wrong. It is a structured observation that gives the clinician examples of how your child communicates, plays, and interacts. The scores are combined with your child’s history and other assessments to decide whether the diagnostic criteria for autism are met, and to describe your child’s strengths and needs.

Is the ADOS-2 the gold standard for autism diagnosis?

The ADOS is often described as a gold-standard observation tool, and it performs well in research. But the true gold standard is an experienced clinician’s judgment that combines history, observation, and other testing. Guidelines from NICE and the AAP say the ADOS-2 should support, not replace, that judgment, and that no single tool should be used alone.

Can the ADOS-2 be done online?

The standard ADOS-2 is designed to be done in person. During and after the COVID-19 pandemic, some services began using telehealth tools designed for video assessment, such as the TELE-ASD-PEDS for toddlers. Research shows these can work well for many young children, though some still need an in-person assessment. Ask your provider what they offer.

What if my child acts differently during the ADOS-2?

This is common. Some children are quieter, more social, or more upset in a new place. Clinicians are trained to account for this, and they use your description of your child’s everyday behavior alongside the observation. If the session did not reflect your child, say so, and share videos or reports from home or school.

References

1. Lord C, Rutter M, DiLavore PC, Risi S, Gotham K, Bishop SL, Luyster RJ, Guthrie W. Autism Diagnostic Observation Schedule, Second Edition (ADOS-2). Product information. Pearson Clinical UK (publisher of record in the US: Western Psychological Services, 2012). Link
2. Hyman SL, Levy SE, Myers SM; Council on Children With Disabilities, Section on Developmental and Behavioral Pediatrics. Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. Pediatrics. 2020;145(1):e20193447. Link
3. Lord C, Risi S, Lambrecht L, Cook EH Jr, Leventhal BL, DiLavore PC, et al. The autism diagnostic observation schedule-generic: a standard measure of social and communication deficits associated with the spectrum of autism. J Autism Dev Disord. 2000;30(3):205-223. Link
4. Luyster R, Gotham K, Guthrie W, Coffing M, Petrak R, Pierce K, et al. The Autism Diagnostic Observation Schedule-toddler module: a new module of a standardized diagnostic measure for autism spectrum disorders. J Autism Dev Disord. 2009;39(9):1305-1320. Link
5. Shaw KA, Williams S, Patrick ME, Valencia-Prado M, Durkin MS, Howerton EM, et al. Prevalence and Early Identification of Autism Spectrum Disorder Among Children Aged 4 and 8 Years – Autism and Developmental Disabilities Monitoring Network, 16 Sites, United States, 2022. MMWR Surveill Summ. 2025;74(2):1-22. Link
6. Randall M, Egberts KJ, Samtani A, Scholten RJ, Hooft L, Livingstone N, et al. Diagnostic tests for autism spectrum disorder (ASD) in preschool children. Cochrane Database Syst Rev. 2018;7(7):CD009044. Link
7. Lebersfeld JB, Swanson M, Clesi CD, O’Kelley SE. Systematic Review and Meta-Analysis of the Clinical Utility of the ADOS-2 and the ADI-R in Diagnosing Autism Spectrum Disorders in Children. J Autism Dev Disord. 2021;51(11):4101-4114. Link
8. National Institute for Health and Care Excellence. Autism spectrum disorder in under 19s: recognition, referral and diagnosis. Clinical guideline CG128. Published 28 September 2011; last updated 20 December 2017 (minor changes 2021-2025). Link
9. Lord C, Rutter M, Le Couteur A. Autism Diagnostic Interview-Revised: a revised version of a diagnostic interview for caregivers of individuals with possible pervasive developmental disorders. J Autism Dev Disord. 1994;24(5):659-685. Link
10. Corona LL, Wagner L, Hooper M, Weitlauf A, Foster TE, Hine J, et al. A Randomized Trial of the Accuracy of Novel Telehealth Instruments for the Assessment of Autism in Toddlers. J Autism Dev Disord. 2024;54(6):2069-2080. Link
11. NHS. Autism assessments. Page last reviewed 6 May 2026. Link

Professional review: this guide is waiting for review by a qualified clinician. It was written and checked against the published sources listed above. How we check our guides.

This guide is general education, not medical advice. Always talk to your child’s doctor or care team. Last checked: October 2026.