The Definition of Dyslexia Just Changed — Here's What It Means for Your Family

In October 2025, the Board of Directors of the International Dyslexia Association approved a new definition of dyslexia. It replaces the one written in 2002 — the definition that has shaped how schools, psychologists and state laws have talked about dyslexia for more than twenty years.

The full rationale was published in April 2026 in Annals of Dyslexia by Hugh Catts, Charles Haynes and Malatesha Joshi, who led the revision. It is a dense academic paper. But buried in it are two changes that could directly affect whether your child gets identified — and a third that changes what a school can reasonably ask you to accept.

The new definition

Dyslexia is a specific learning disability characterized by difficulties in word reading and/or spelling that involve accuracy, speed, or both and vary depending on the orthography. These difficulties occur along a continuum of severity and persist even with instruction that is effective for the individual's peers. The causes of dyslexia are complex and involve combinations of genetic, neurobiological, and environmental influences that interact throughout development. Underlying difficulties with phonological and morphological processing are common but not universal, and early oral language weaknesses often foreshadow literacy challenges. Secondary consequences include reading comprehension problems and reduced reading and writing experience that can impede growth in language, knowledge, written expression, and overall academic achievement. Psychological well-being and employment opportunities also may be affected. Although identification and targeted instruction are important at any age, language and literacy support before and during the early years of education is particularly effective.

It is longer than the old one. That is not padding — nearly every added clause is closing a door that was being used to turn kids away.

What changed, and why it matters

1. The IQ discrepancy is gone

The 2002 definition said that reading difficulties were "often unexpected in relation to other cognitive abilities." That single phrase caused two decades of damage.

In practice, "other cognitive abilities" got read as "intelligence," and a child had to show a gap between a strong IQ and weak reading to be identified. If a child's IQ score was merely average, or low, the reasoning went: their reading is not unexpected, so this is not dyslexia.

Part of why that idea took hold, the authors suggest, is the popular image of the brilliant dyslexic — the widespread portrayal in media of highly intelligent or creative people with dyslexia. Those people are real. But they are not the pattern.

Dyslexia occurs across the entire range of intellectual ability, and the spread of intelligence among dyslexic people looks like the spread among everyone else. As the paper puts it: "like those without dyslexia, most individuals with dyslexia have normal or even below normal intelligence." That is a statement about how intelligence is distributed in any group of people — most of us sit at or below the middle, by definition — not a claim that dyslexia comes with lower intelligence. It doesn't.

Which is exactly why the discrepancy idea fails. If dyslexic children span the full ability range, then requiring a gap between IQ and reading only finds the ones at the top of it. And children with dyslexia who have lower IQs show the same word reading difficulties, the same underlying causes, the same brain patterns, and the same response to instruction as children with dyslexia who have higher IQs.

What this means for you: if anyone tells you your child cannot be dyslexic because their cognitive testing did not show a big enough gap, that reasoning is no longer supported by the definition — and has not been supported by the research for years.

This is not the same as saying intelligence never matters. A child with significantly low scores on standardized IQ measures and major challenges in adaptive functioning — language, social behavior, self-care — would not be identified as dyslexic. They need a broader approach. But an ordinary average IQ is not a disqualifier, and never should have been.

2. Hard circumstances no longer rule your child out

The old definition called dyslexia "neurobiological in origin." The new one says the causes "involve combinations of genetic, neurobiological, and environmental influences that interact throughout development."

That sounds like an academic nicety. It is not. In some districts, a child living in poverty, or learning in a language that is not spoken at home, or carrying a history of adverse experiences, gets those factors named as the explanation for their reading difficulty — and is quietly steered away from a dyslexia evaluation.

The paper takes that head-on, saying the new definition "challenges the current practice in some settings and locales of excluding from a dyslexia diagnosis individuals with significant environmental risk." Having an environmental risk, they write, "in no way rules out the possibility that a child has dyslexia."

What this means for you: difficult circumstances and dyslexia are not competing explanations. A child can have both, and having the first does not disqualify them from being identified with the second.

3. Phonological problems are "common but not universal"

This one will surprise people who have been told that dyslexia is a phonological deficit.

The 2002 definition said reading difficulties "typically result from a deficit in the phonological component of language." The 2025 version steps back to "common but not universal."

The evidence behind the change is striking. In one study, only about half of the kindergarteners who were later identified with dyslexia had shown a significant deficit in phonological awareness. Run the other direction and you get the same result: only about half the children with a significant phonological awareness deficit at the start of kindergarten had dyslexia by the end of second grade. A large meta-analysis of 155 samples found that word decoding correlates only moderately with phonological awareness.

Phonological difficulty is real and it is common. It is just not the whole story, and it is not a gate.

What this means for you: a phonological processing test that comes back looking fine does not rule dyslexia out. Neither does a weak one rule it in. The definition is explicit that no behavioral, genetic, or neurological marker — beyond persistent difficulty with word reading and spelling itself — is reliable enough to identify dyslexia at the individual level.

The new definition also adds two things alongside phonology: morphological processing (understanding how prefixes, suffixes and root words work), and early oral language weaknesses, which "often foreshadow literacy challenges." If your child had a late or bumpy start with talking, that is worth mentioning at an evaluation.

4. New: it depends on the language

A genuinely new component is that difficulties "vary depending on the orthography" — the writing system being learned.

English is an outlier. Its spelling is far less consistent than most alphabetic languages, so English-speaking children with dyslexia typically struggle with both accuracy and speed. In more transparent languages such as Finnish, Spanish or Italian, children generally reach near-ceiling accuracy within about a year of instruction, and dyslexia shows up mainly as slowness rather than errors.

What this means for you: if your family is multilingual, this matters. A child who reads Spanish accurately but slowly is not necessarily fine — and a definition written only around English reading errors would have missed them.

5. Still a "disability" — on purpose

The authors acknowledge that some people object to the word disability, and that "learning difference" or "neurodiversity" avoid the negative associations. They kept "specific learning disability" anyway, for a concrete reason: it aligns with the Individuals with Disabilities Education Act, "thereby preserving the legal rights and educational services to which individuals with dyslexia are entitled."

Softer language, they argue, "can also obscure the reality that these challenges are genuine, persistent, and have significant educational and social implications."

You can use whatever word you like at home. But in an IEP meeting, the word disability is doing legal work.

What stayed the same

• Word-level reading and spelling remain the core. Comprehension problems are downstream consequences, not the defining feature.
• A continuum of severity, with no universally agreed cut-point. Estimates of how many people are dyslexic still range from roughly 5–10% up to one in five, depending on where the line is drawn.
• Persistence despite good instruction. Difficulties that "persist even with instruction that is effective for the individual's peers."

That last phrase carries a warning the authors state directly: it is not an endorsement of a "wait to fail" approach. They point out that identification is too often postponed well into elementary school, "far after the time that intervention is the most effective" — a problem the field calls the dyslexia paradox. Persistence can be visible as early as the first year of instruction.

What the definition does not do

Worth knowing before you take it into a meeting: the definition "carries no direct legislative or regulatory authority." It cannot compel a school to fund anything. Its influence depends entirely on how states and districts choose to interpret it.

It also deliberately says nothing about the conditions that often travel with dyslexia, even though the paper acknowledges them: developmental language disorder co-occurs in roughly 30% of population samples and up to about 50% of clinical ones, and ADHD overlaps with dyslexia in the 20–40% range. Those are separate diagnoses, not part of dyslexia itself.

The bottom line

The 2025 definition is not a dramatic reinvention. Word reading and spelling difficulty is still the heart of it. What has changed is the set of reasons a child can be excluded — and three of those reasons were doing real damage.

If your child was evaluated in the last decade and told they did not qualify because their IQ gap was too small, because their circumstances explained it, or because their phonological scores looked fine, it may be worth revisiting that conversation. The definition the field is working from has moved.

The authors close by calling it a "living document" that will change again as the science does. That is worth remembering in both directions: it is the best current thinking, not the final word.