Dyslexia and Developmental Language Disorder: What Parents Should Know
Updated: Oct 28
Two related but distinct profiles
Dyslexia primarily concerns difficulties in learning to read and spell. Developmental language disorder (DLD) involves persistent difficulties understanding and/or using language that affect everyday communication or learning and are not associated with a known differentiating biomedical condition.
Some children experience both. Because spoken language supports reading comprehension, vocabulary learning and classroom participation, the difficulties can interact. However, weak reading does not automatically mean DLD, and a child with DLD does not necessarily have dyslexia.
What language difficulties may look like
A child may struggle to understand long spoken explanations, learn new words, follow complex grammar or put ideas into clear sentences. They may appear to understand familiar classroom routines but become confused when the wording changes.
Some children speak readily and use long sentences while still missing subtle meanings or having difficulty finding precise words. These patterns deserve attention even if reading accuracy seems reasonable. Language needs can be less visible than spelling errors.
Where dyslexia may be more noticeable
A pupil with dyslexia may understand a story well when it is read aloud but find decoding the printed text slow and effortful. Spelling may remain inaccurate despite appropriate teaching.
In contrast, a pupil with significant language-comprehension difficulties may struggle with the meaning of a passage even when someone else reads it to them. These are illustrative contrasts, not diagnostic rules: a learner can have difficulties in both decoding and language comprehension, and reading fluency can further complicate the picture.
Why vocabulary scores need careful interpretation
Assessments may include different language tasks: matching spoken words to pictures, explaining word meanings, naming pictures or answering spoken questions. A low score on one task does not establish DLD. It may reflect the particular demands of recognition, retrieval, comprehension, attention or unfamiliar vocabulary.
A marked contrast between tasks deserves explanation rather than an automatic label. The assessor should consider developmental language history, everyday communication and whether difficulties are present across contexts.
Who assesses what?
Specialist dyslexia assessors examine literacy and relevant cognitive or language skills within their professional remit. Speech and language therapists are key professionals for assessing and supporting spoken-language difficulties, including possible DLD.
A dyslexia assessment may identify reasons to seek further language investigation, but it should not be presented as a full speech and language assessment unless the assessor has the appropriate qualifications and has undertaken one. Schools can also gather evidence of classroom language needs.
Helpful support in lessons
Teach important words explicitly, revisit them in different contexts and check understanding with examples rather than asking only ‘Do you understand?’ Break lengthy spoken instructions into shorter steps and pair them with written or visual cues.
Give processing time before expecting an answer. For a pupil who also struggles with decoding, make subject content accessible while providing appropriate literacy teaching. Vocabulary support should address understanding and use, not merely memorising definitions for a test.
Questions to discuss with school
Ask whether difficulties occur mainly when the child reads independently or also when material is explained aloud. Can they retell a story, understand subject vocabulary and follow multi-part spoken instructions?
Are they able to explain what they know in their own words? Ask what school has observed over time and whether the SENCo recommends speech and language involvement. Examples from home and school are valuable because performance may vary with familiarity and context.
A sensible next step
If there are persistent concerns about understanding or expressing spoken language, discuss them with the SENCo and relevant health or speech and language service rather than assuming that a dyslexia diagnosis explains everything.
Support can begin while assessment questions are explored. The most useful outcome is a clear description of which demands cause difficulty, which strengths can be used and what changes will help the child communicate and learn.
Discussing an assessment
Mark Trewby offers diagnostic dyslexia assessments online across the UK for ages 11–21 and face-to-face in Bournemouth for ages 8–21. The £400 fee includes a personalised report within seven working days and feedback. An introductory conversation can help you discuss suitability; a diagnosis cannot be promised in advance.