An adult autism assessment is a structured set of conversations, and sometimes observation, in which a trained clinician decides whether your lifelong pattern of traits meets the criteria for autism. It is not a pass or fail test, and it can also identify other explanations or conditions that sit alongside autism. This page covers the appointment itself. For routes, waiting times and costs, see our guide to getting an autism assessment in England and Ireland.
In England, NICE guideline CG142 says the assessment should be done by trained and competent professionals, working as a team across more than one profession. In Ireland, AsIAm states that psychologists and psychiatrists carry out adult assessments, and that there is no public adult pathway. Ireland does not currently regulate psychologists, so AsIAm suggests checking whether a clinician is a Chartered member of the Psychological Society of Ireland and asking to see their certificate.
CG142 lists what an adult assessment should look at: the core features in childhood and in adulthood, early development, behavioural difficulties, how you function at home, in education and at work, past and current physical and mental health conditions, other neurodevelopmental conditions, and sensory sensitivities and attention to detail. Core features should also be observed directly, especially in social situations.
The clinician will ask about your early life. Where possible they involve someone who knew you as a child, such as a parent or sibling, or use documents such as school reports. If nobody is available, tell them; assessors work with what exists.
For adults without a learning disability, CG142 names several structured tools: the Adult Asperger Assessment, the ADI-R (an interview with an informant), the ADOS (an observational assessment), the ASDI and the RAADS-R. The guideline names the original edition of the ADOS; a later edition, the ADOS-2, is now in use. In Ireland, a factsheet from the youth information service spunout notes that no specific tool is required, and AsIAm describes the process as in-depth interviews against the DSM-5 criteria. What matters is that the conclusion rests on a full history and on more than one source, not on a single questionnaire.
The clinician also considers conditions that can look similar or occur alongside autism, such as anxiety, depression, OCD, social anxiety and ADHD. CG142 advises against routine blood, genetic or brain scan tests as part of diagnosis. See autism and ADHD together.
If you are identified as autistic, you should receive a written report covering how the assessment was done, your strengths and difficulties, and recommendations (AsIAm). CG142 says every adult who is diagnosed should be offered a follow-up appointment to talk through what the diagnosis means and what support they might want. If you are not diagnosed, the clinician should explain why and what else may account for your difficulties.
Everything above is taken from NICE CG142 (recommendations 1.2.5 to 1.2.11 and 1.2.18), AsIAm's guidance on adult diagnosis, and the spunout factsheet on adult autism diagnosis. We did not use clinic websites as sources, so we do not state how long an assessment takes or what it costs here, because the figures we found came from clinics. Last checked 25 October 2026. This article describes how assessment services work. It is general information, not medical advice, and it cannot assess your individual situation. Reviewed by: Proco Team.