Is it DLD or Dyslexia?

Developmental language disorder (DLD) and dyslexia are both lifelong conditions that affect academic performance—and virtually every other area of a person’s life. Learning to distinguish between the similar-looking effects of these two conditions can help you anticipate potential difficulties, individualize interventions, and identify which supports and accommodations will be most meaningful. 

Even among school-based practitioners who regularly work with students who have one or both conditions, considerable confusion exists when it comes to defining the terms (DeLuca et al., 2025). 

An important note: In a 2023 letter addressed to the president of the American Speech-Language-Hearing Association (ASHA), the Office of Special Education programs noted that language impairments such as DLD can be addressed under the existing disability categories defined within the Individuals with Disabilities Education Act (IDEA) (Hogan et al., 2023). 

Can You Have Dyslexia and DLD at the Same Time?

Yes. Researchers say it’s not uncommon for people with DLD to have learning disorders such as dyslexia and dyscalculia (Nitin et al, 2022).  In fact, the National Institute on Deafness and Other Communication Disorders (NIDCD) considers DLD to be a risk factor for learning disabilities, making it around six times more likely that someone with DLD will be diagnosed with a reading or spelling disability by the time they reach their adult years (NIDCD, 2023). In one long-term study, male children who had been diagnosed with DLD and had a family member with a specific learning disorder had a 54% chance of having a specific learning disorder themselves (Rinaldi et al., 2023).  

What Are the Similarities and Differences Between DLD and Dyslexia? 

Dyslexia and DLD are both neurodevelopmental conditions, and they have some similarities. Both emerge in early childhood and continue as a person grows. Both conditions are linked to differences in brain structure and nerve networks—but different areas of the brain are involved in each condition. Similarly, while the two conditions have effects that can look alike, those effects may have different origins.  
Here’s a brief look at skills that may be affected by these neurodevelopmental conditions, along with tips for telling them apart

Phonology

Phonological awareness is the ability to identify and work with phonemes (the individual sounds that make up words). Skills such as rhyming, sound matching, and sound/symbol connection are typically included under the umbrella of phonological awareness.  

Dyslexia and DLD can affect people’s phonological awareness, making it harder to break words into syllables, to blend letter sounds, and to distinguish letter sounds from each other. When people have both dyslexia and DLD, phonological awareness tasks may be even harder for them than they are for people with just one of the conditions (Snowling et al., 2019).  

In one study, preschool children with DLD had particular difficulty adding syllables and identifying and adding phonemes (Moraleda-Sepúlveda & López-Resa, 2022). In another study, children with DLD had trouble with phoneme deletion tasks (Oliviera et al., 2020). 

Word Reading and RAN

Word reading difficulties are a key feature of dyslexia, and they’re not uncommon in students with DLD. Rapid automatized naming (RAN), which is the ability to quickly recall and name colors, letters, numbers, and other symbols, is considered by some experts to be the basis of word reading skills (de Bree et al., 2022).  

RAN is an area of difficulty for students with dyslexia. In fact, RAN is considered a “universal marker” for dyslexia (Carioti et al., 2022). Some students with DLD also have difficulties with RAN, but a 2020 study found that they had fewer errors in RAN tasks than study participants who had dyslexia. Instead, children with DLD made more errors in nonword repetition tasks (Oliviera et al., 2020).  

Morphology  

Morphology is word-building: putting words together from smaller units of meaning. Children as young as 18 months can play with word forms to make new words, often starting with word features that indicate singular or plural numbers. From there, they might go on to learn word endings that change the meaning of a word, such as adding -er to indicate someone who does an action. Drive becomes driver, for example.  

Morphology is important in the development of oral language, reading, and spelling. It’s a skillset that may be impaired in some people with dyslexia (Melloni & Vender, 2022).  It may be even more common in people with DLD. In fact, some experts consider morphological difficulties to be “clinical marker” of DLD.  

In studies, verb tense, pronouns, and formation of the plural are often areas of concern in people with DLD. These error patterns may vary slightly from one language to another (Moraleda-Sepúlveda & López-Resa, 2022). In students with dyslexia, decoding complex words and “function” words may be a challenge. Researchers recommend assessing children’s “linguistic profile” in a dyslexia evaluation to find out whether an error pattern is related to morphology or phonology (Casani et al., 2022).  

Researcher Evelyn Fisher and her team summarized the differences like this:

Children with language impairment have difficulty in primarily nonphonological language skills of syntax and morphology, while children with dyslexia have impairments primarily in phonological processing. (Fisher et al., 2019)

What Are Best Practices for Assessing DLD and Dyslexia? 

1. Assess broadly. Evaluating early literacy skills, reading skills, and language skills can help you create a detailed language profile for the person involved. Comprehensive assessment can help you determine whether needs are related to reading and literacy or whether they extend to other expressive or receptive language skills.
2. Assess early. Because DLD and dyslexia are both neurodevelopmental conditions, indicators may be present long before a child enters school. Earlier identification and intervention may prevent some educational, social, and mental health effects.
3. Gather data from multiple sources. Include detailed family and developmental histories when possible. If a student is learning multiple languages, take special care to explore that child’s language history, so you can determine whether any difference is related to language learning. Other risk factors for DLD include delayed gesture production, limited receptive and/or expressive vocabulary size, and a lack of two-word combinations at 30 months (Sansavini et al., 2021). 

Key Message

DLD and dyslexia share many characteristics, and some children experience both conditions at the same time. Careful, comprehensive evaluation can make diagnostic decisions clearer and can lead to more effective instruction and intervention.