How is dyslexia diagnosed?
A dyslexia diagnosis comes from a full assessment by a qualified professional, not from a single test. Here is who can assess, what happens during the assessment, how it differs from a screening, and how to get ready for it.
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Short answer
Who can diagnose dyslexia, and what does the assessment involve?
Dyslexia is diagnosed through a full assessment by a qualified professional, such as an educational psychologist, a school psychologist or a specialist assessor with a recognised qualification. The assessment combines a developmental and educational history with standardised tests of word reading, reading of made-up words, reading fluency, spelling, phonological awareness, rapid naming and memory, and rules out other explanations such as hearing, vision or lack of teaching. An online screening can show signs worth following up, but it cannot diagnose dyslexia.
- There is no single blood test, brain scan or quiz that diagnoses dyslexia.
- Assessors look for persistent difficulty with accurate or fluent word reading and spelling, despite adequate teaching.
- ICD-10 lists specific reading disorder as F81.0; ICD-11 lists developmental learning disorder with impairment in reading as 6A03.0.
- Screening decides whether to assess; an assessment decides whether the difficulties add up to dyslexia.
How to prepare for a dyslexia assessment
A little preparation makes the assessment more useful and the report easier to act on.
- 1
Write down your questions
Note what worries you and what you want to know: for example, why reading is slow, what support to ask for, or whether attention or math difficulties are also involved.
- 2
Gather school records
Collect school reports, reading assessments, any intervention records and examples of recent writing. For adults, old reports and a note of past difficulties help too.
- 3
Note family history
Write down whether parents, siblings or other relatives had reading or spelling difficulties. Dyslexia often runs in families.
- 4
Rule out hearing and vision
Book a recent hearing and eye check if there has not been one. Assessors need to know these are not the explanation.
- 5
Prepare the child or adult
Explain that the session is a set of puzzles and reading tasks, not an exam to pass or fail, and make sure they have slept and eaten well.
How dyslexia is diagnosed: the short version
Dyslexia is diagnosed when a qualified assessor finds persistent difficulty with accurate or fluent word reading and spelling that is not better explained by something else, such as a hearing or vision problem, a lack of teaching or a general learning difficulty. The difficulty usually sits in processing the sounds inside words, and it shows up across several tests rather than in one score.
There is no blood test, brain scan or single questionnaire that diagnoses dyslexia. Current research sees dyslexia as dimensional: reading ability varies along a continuum, and a diagnosis marks the point where difficulties are severe and persistent enough to need support. That is why a good assessment gives a detailed profile, not only a yes or a no.
Dyslexia also rarely comes from a single cause. The multiple-deficit view holds that several risks, genetic and environmental, add up; that is one reason why assessors ask about attention, language, math and family history as well as reading.1,2,3
Who can diagnose dyslexia
Dyslexia is usually assessed by an educational psychologist, a clinical or school psychologist, or a specialist teacher-assessor who holds a recognised qualification in assessing specific learning difficulties. Speech and language professionals are often involved when there are wider language difficulties, and doctors are involved when hearing, vision or other health questions need to be ruled out.
In the United States, parents can ask their child's public school, in writing, to evaluate the child for special education under the Individuals with Disabilities Education Act (IDEA). A school psychologist and other staff then assess the child, and dyslexia falls under the category of a specific learning disability. Schools do not always use the word dyslexia in their reports, so it is fine to ask how they describe the findings. Private evaluations by a psychologist are another route.
Other countries have their own routes: through the school, the national health service, a university disability service or private practitioners. Because the rules and recognised qualifications differ, check which assessments your school, college or employer accepts before you book one.4
What a dyslexia assessment includes
Most assessments take a few hours, sometimes split over more than one session, and are followed by a written report. They generally cover the areas below, tuned to the person's age.5,6,7,8
| Area | What the assessor looks at |
|---|---|
| History | Early speech and language, family history of reading difficulty, schooling, previous support, hearing and vision |
| Word reading | Reading real words aloud, both accuracy and speed |
| Decoding | Reading made-up words, which cannot be recognised from memory and show whether words can be sounded out |
| Reading fluency and comprehension | Reading passages aloud and silently, and answering questions about them |
| Spelling and writing | Spelling dictated words and writing a short piece, including speed of writing |
| Phonological awareness | Hearing, splitting and changing the sounds inside words |
| Rapid naming | Naming rows of colors, objects, letters or digits as fast as possible |
| Memory and processing speed | Remembering spoken sequences and working quickly on simple tasks |
| Underlying ability | In many assessments, verbal and nonverbal reasoning, to understand the whole profile |
How to test for dyslexia: screening versus assessment
A screening is a short check that shows whether signs of dyslexia are present. It can be a questionnaire, a set of short games or a quick reading task, and it is often done by a teacher, a parent or online. Screening helps decide who should go on to a full assessment. It cannot diagnose dyslexia, and a result without signs does not rule it out.
An assessment is the full process described above, carried out by a qualified professional with standardised tests. It gives a detailed profile, a conclusion about whether the difficulties fit dyslexia, and recommendations for support.
Early signs can often be seen before a child is taught to read: weak phonological awareness, slow rapid naming, slow learning of letter names and sounds, and a family history of dyslexia. Children with a family history have a much higher risk, about 45% in one meta-analysis. You do not need to wait for a child to fail before asking questions.
The free dyslexia test for children is a screening: six short games in about 8 minutes that give a skills profile and say plainly when an assessment is worth asking for. Adults can take the dyslexia test for adults.9,10
Dyslexia diagnosis codes in ICD-10 and ICD-11
Reports and insurance forms sometimes include a classification code. In the World Health Organization's ICD-10, dyslexia is usually coded as F81.0, specific reading disorder. In ICD-11, the current version, the matching code is 6A03.0, developmental learning disorder with impairment in reading.
The code does not change what support a person needs. It is a label that helps different services talk about the same thing; the detailed profile in the report is what schools and employers can act on.11,12
Dyslexia assessment cost and waiting times
Public school evaluations in the United States are provided at no cost to families. In other countries, assessments through schools or public services may also be free, but waiting lists can be long. Private assessments are usually faster and can be expensive, and prices vary widely by country, city and the qualifications of the assessor.
When comparing options, ask what the fee includes (the testing sessions, the written report, a feedback meeting), whether the report will be accepted by your school, college, university or exam board, and how long you will wait for the report after testing.
While you wait, you do not have to stand still. Short, regular practice of letter-sound links and blending sounds into words is the approach with the most consistent evidence for struggling readers, and it helps whether or not the assessment confirms dyslexia. Our guide on how to help a child with dyslexia explains where to start.13
