The October 2025 revision of the definition of dyslexia reflects significant advances in research, global consensus, and understanding gained since the 2002 IDA working definition was published. It maintains continuity with established principles while integrating new insights into the nature, causes, and impacts of dyslexia.
Use the following link for more detailed information 2025 Dyslexia Definition – International Dyslexia Association
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 early years of education is particularly effective.
Rationale for the IDA Updated Definition of Dyslexia (2025)
- Alignment with international and federal terminology: The updated definition continues to identify dyslexia as a specific learning disability, consistent with the World Health Organization (ICD-10) and the Individuals with Disabilities Education Act (IDEA), ensuring continued access to legal protections and educational services.
- Broader recognition of literacy difficulties: The definition clarifies that dyslexia involves persistent difficulties in word reading and/or spelling affecting accuracy and/or speed, emphasizing word-level literacy skills, and acknowledging that manifestations vary across different languages and writing systems.
- Emphasis on persistence and instructional response: By specifying that these difficulties persist even with effective instruction, the definition distinguishes dyslexia from temporary learning challenges. It recognizes that instruction quality and peer progress are essential for fair identification.
- Updated understanding of causes: The new wording recognizes that dyslexia arises from complex interactions among genetic, neurobiological, and environmental influences across development. This reflects the field’s consensus that dyslexia is multifactorial, not the result of a single cause.
- Expanded view of underlying processes: While reaffirming the importance of phonological processing difficulties, the revised definition includes morphological and oral language weaknesses as common—though not universal—features. It also removes outdated references to IQ or cognitive discrepancy, aligning with evidence that dyslexia occurs across levels of intelligence.
- Recognition of co-occurring conditions and secondary consequences: The definition acknowledges frequent co-occurrence with conditions such as ADHD, DLD, and dyscalculia, while distinguishing them as separate. It also elaborates on the secondary impacts of dyslexia—reduced reading experience, limited vocabulary growth, academic challenges, and effects on mental health and psychological well-being and future employment opportunities.
- Inclusion of early identification, early intervention, and psychological well-being: For the first time, the definition underscores the critical importance of early screening and intervention, reflecting strong research, evidence, and public support for proactive educational approaches that improve long-term outcomes. Another important addition is the impact dyslexia can have on psychological well-being, including anxiety, low self-esteem, and depression, and its potential effects on career and employment opportunities later in life.
The 2025 definition updates the understanding of dyslexia to reflect two decades of scientific and educational progress. It provides a more inclusive, research and evidence-based, and globally relevant framework that better guides early identification, early intervention, and policy.