This is the question I get asked more than any other. Parents ask it, teachers ask it, and a good number of adults ask it about themselves, sometimes after wondering for thirty years. It sounds like it should have a tidy answer. It really doesn’t, and getting it right matters, because the way we define dyslexia decides who gets help and who slips quietly through.

So here is how I’d explain it, as someone who assesses for dyslexia, researches it, and has spent a career working alongside the young people who have it.

A working definition

Dyslexia is a specific learning difficulty, or SpLD, that mostly affects the skills involved in reading and spelling accurately and fluently. It belongs to a wider family of specific learning difficulties that includes dyscalculia and developmental coordination difficulties, and it very often turns up alongside them rather than on its own.

The most recent definition for dyslexia was published in 2025 following a Delphi study commissioned by SASC. You can read it here on the British Dyslexia Association website. Phonological skills, working memory and processing are implicated and it often is spotted when children find reading, writing or spelling difficult.

Dyslexia gets argued about a great deal, as I’ve written in my chapter “It’s a Battle!” (Ross, 2021), but a good definition gives us characteristics we can actually assess. It stops dyslexia being a vague word we reach for whenever a child struggles, and turns it into a recognisable pattern. Usually that pattern involves difficulty with phonological awareness (hearing and playing with the sounds in words), verbal memory, and processing speed. Reading and spelling are where it tends to show up first. But because so much of school runs on those skills, its reach goes well beyond the literacy lesson.

Roughly one in ten people is dyslexic. In my research on assistive technology (Ross, 2024) I set out the wider picture: NHS figures put dyslexia at around 10 per cent of the population, and the Department for Education recorded about 11 per cent of pupils in England as having a specific learning difficulty in January 2022. Put plainly, most teachers have several dyslexic learners in every class, whether or not anyone has ever spotted them.

Dyslexia is real, and it matters that we treat it that way

You’ll still hear people say dyslexia doesn’t really exist as a distinct thing. I want to be plain about why that idea does harm. If dyslexia isn’t real, then a child’s difficulty with reading must be their own fault, or their parents’ fault, and the school has nothing it needs to do differently. The whole weight of it lands on the family.

What I found in my own research with parents and carers, in Supporting a child with dyslexia (Ross, 2019) in the British Journal of Special Education, was more hopeful than that. Families who understood dyslexia as a real difference in how a brain handles certain information, shaped by how school and society respond to that difference, were able to turn it into a positive story. Their child stopped being someone who was failing and became someone who learns differently and needs the right conditions to do well.

And this isn’t only about how the adults make sense of it. When I looked at young people’s own experiences, in a study I called “I’m Dyslexic but What Does That Even Mean?” (Ross, 2021), the way a young person understood their own dyslexia shaped how they got on with everyone around them. A young person who has decided they are “thick” moves through school very differently from one who knows they have a particular profile that can be worked with. The words we use become the story a child tells about themselves.

A few things dyslexia is not

There are some myths I find myself unpicking almost every week.

It isn’t a sign of low intelligence. Dyslexic people sit right across the ability range, and plenty are quick, original thinkers whose reading simply doesn’t keep pace with their ideas.

It isn’t just “reading letters backwards”. Reversals do happen for some children, but they aren’t the heart of it, and a child who never reverses a letter can still be very dyslexic.

It isn’t caused by lazy children or poor teaching. Good teaching helps enormously, and I’ll come back to that. But the underlying difference is real, and it stays put even when the teaching is excellent.

And you don’t grow out of it. Dyslexia is lifelong. What changes over time is how well someone learns to work with it, and how much room the people around them are willing to make.

How is dyslexia identified?

It helps to keep two things separate here.

Screening gives you an early steer on whether a young person is likely to be dyslexic. Teachers, SENCos and trained teaching assistants can use screeners to flag concerns, and that early flag is exactly where things ought to begin.

A full diagnostic assessment is the detailed piece of work. A qualified assessor sits with the young person one to one and works through a set of standardised tests, looking at underlying ability, the cognitive processing skills dyslexia tends to affect, and attainment in reading, spelling and sometimes writing and maths. What comes out of it is a report that explains the profile in plain terms and, most usefully of all, says what should happen next.

If you’d like to know what that actually feels like on the day, I’ve written about it in what happens in a dyslexia assessment. And if you think an assessment might be your next step, you can read about how I work here.

So what actually helps?

This is the part I care about most, because a label that leads nowhere helps nobody.

Nearly everything that supports dyslexic learners supports everyone else in the room too. That thread runs right through my work, from my early research on teachers’ agency (Ross, 2017) to the review I wrote for the Council for Science and Technology (Ross, 2020). “Dyslexia-friendly” teaching is mostly just good teaching that someone has bothered to make visible. Clear slides. Resources that aren’t cluttered. Information offered in more than one way.

Some of the small things make a surprising difference. A soft copy of the slides, so a young person can work through them at their own pace. The accessibility tools already sitting inside Office 365 and Google Workspace. Printing on coloured paper. Giving instructions a couple at a time instead of ten at once. Letting a young person read with assistive technology rather than waiting for a grown-up to be free. That last one matters more than people expect, and I’ve researched it directly (Ross, 2024): young people made real gains with a reading device, and what struck me most was how much they valued being able to get on by themselves.

None of this needs a heroic budget. It needs knowing what to do, being allowed to do it, and actually bothering to.

Where that leaves us

Dyslexia is a real, lifelong, recognisable difference in how a person handles written language. It’s common, it has nothing to do with how clever you are, and it responds well to the right support. In my experience, what does the damage is rarely the dyslexia itself. It’s how often it goes unnoticed, and how much of the fallout lands on families, which is something I documented in the Human Cost of Dyslexia report (Ross and Hicks, 2019).

Understanding what dyslexia really is, is where that starts to change.

Questions people often ask

Is dyslexia a disability? Legally, in the UK, dyslexia can count as a disability under the Equality Act 2010 where it has a substantial and long-term effect on everyday activities. Plenty of dyslexic people don’t think of themselves as disabled, and that’s fine too. What matters in practice is that reasonable adjustments should be made, in education and at work.

At what age can a child be assessed for dyslexia? Signs can be spotted early, and early support should never wait for a formal diagnosis. Full diagnostic assessments become more reliable once a child has had enough teaching of reading behind them, often from around age seven, though I assess older children, teenagers and adults all the time, including students applying for Disabled Students’ Allowance.

Do we need a diagnosis to get support? In principle, no. Good teaching supports the difficulty whether or not there’s a formal label. In reality, a diagnostic assessment often opens the door to the right support, to exam access arrangements, and to a clear plan, which is why so many families go for one.

Is dyslexia genetic? It does tend to run in families, and research keeps identifying genes and genetic variants linked to it, work I talked about when I commented for The Guardian in 2022. If one person in a family is dyslexic, it’s well worth keeping a thoughtful eye on their siblings.

References and further reading

The research below is by Dr Helen Ross and is publicly accessible; several papers are open access.

See the full list of publications.

Dr Helen Ross is a dyslexia and SEND specialist based in Trowbridge, Wiltshire. She holds a PhD from the University of Bath, is a qualified diagnostic assessor (AMBDA) with a current Assessment Practising Certificate, a 2025 Churchill Fellow, and the author of Literacy Learning Journeys: Dyslexia Across the Ages, 0-18 (Speechmark/Routledge). Her research on dyslexia, families and inclusion has appeared in journals including the British Journal of Special Education and Support for Learning, and she has given evidence to the House of Commons and reviewed for the Council for Science and Technology. She works with families, schools and organisations across the UK and internationally. Book a free 20-minute call.