Developmental Language Disorder (DLD)
Developmental language disorder is a persistent language impairment that is not explained by another medical condition and affects roughly 1 in 14 children.
What DLD is
Developmental Language Disorder, or DLD, is the diagnostic label endorsed by the CATALISE consensus panel for children with persistent language difficulties that carry functional impact and are not better explained by autism, intellectual disability, sensorineural hearing loss, or a neurological condition. It replaces the older term "specific language impairment" in most contemporary practice because "specific" obscured the reality that affected children frequently have co-occurring attention, literacy, or motor difficulties. DLD can affect expressive skills, receptive skills, or — most commonly — both. It is the most common chronic childhood condition that goes under-diagnosed and under-served relative to its population prevalence.
Prevalence
Population studies (Tomblin et al. 1997; Norbury et al. 2016) put DLD prevalence at approximately 7.6% of monolingual kindergarten children — roughly one child in every mainstream classroom of 30.
Diagnostic criteria and defining features
- Persistent language difficulties that interfere with everyday communication or learning
- Language impairment present from early childhood rather than acquired
- Not attributable to autism spectrum disorder, sensorineural hearing loss, intellectual disability, or brain injury
- Poor prognosis without intervention — language skills do not catch up spontaneously by school age
- Standardised language score at least 1.25 SD below the mean on at least two language domains (CATALISE consensus)
Criteria summarised from DSM-5-TR, ICD-11, and ASHA practice guidance. Always cross-reference against the diagnostic manual of record before using in a report.
Clinical presentation
Children with DLD look like typical talkers to a casual observer — they are often highly motivated to communicate, use appropriate gestures, and maintain eye contact. The difficulty surfaces the moment you listen to the grammar. Preschoolers with DLD have short, simple sentences, omit tense and agreement marking ("he going", "she walk yesterday"), and struggle with question forms. School-age children retain a narrow range of sentence structures, avoid subordination, and have word-finding difficulty that looks like mis-naming or long pauses before content words. Narrative retell is a particularly sensitive task because it requires both lexical retrieval and syntactic planning under time pressure. Co-occurring difficulties with working memory, phonological awareness, and literacy are the rule rather than the exception.
“DLD is the disorder that fails to show up on standardised tests about a third of the time. If the parent says "something is off" and the CELF comes back in range, your best next move is a 50-utterance language sample and a non-word repetition task.”
How language sample analysis contributes
Language sample analysis is arguably more useful in DLD than in any other disorder, because the core features — tense omission, sentence-length limitation, lexical narrowness — appear in natural speech but are sometimes missed by standardised test batteries. A 50-utterance conversation sample will reliably capture MLU-M below age expectation, depressed PGU from finite verb morphology errors, and low NDW in a limited-topic conversation. For school-age children, the DSS and IPSyn subscales discriminate DLD from typical peers even when the standardised test battery comes back within the broad average range. Pair LSA with a non-word repetition probe for the strongest screening combination.
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Free tools for Developmental Language Disorder (DLD)
MLU Calculator
Paste a language sample and get Mean Length of Utterance in morphemes and words, total utterances, total morphemes, and the matching Brown's stage. Implements Brown (1973) morpheme counting rules and runs entirely in your browser.
Open toolDSS Calculator
Free Developmental Sentence Scoring (DSS) calculator for speech-language pathologists. Paste 50 sentences, tap weighted points across the eight Lee (1974) grammatical categories — Indefinite Pronouns, Personal Pronouns, Main Verbs, Secondary Verbs, Negatives, Conjunctions, Interrogative Reversals, Wh-Questions — plus the all-correct sentence point, and the calculator returns the live DSS with a per-category breakdown. Mobile-friendly tap-through grid, client-side, no sign-up.
Open toolIPSyn Calculator
Free Index of Productive Syntax (IPSyn) calculator for speech-language pathologists. Score the 56 Scarborough (1990) grammatical items across the Noun Phrase, Verb Phrase, Question/Negation, and Sentence Structure subscales from a 100-utterance language sample. Live IPSyn total, per-subscale subtotals, sample-size guard, mobile-friendly, client-side, no sign-up.
Open toolLanguage Sample Worksheet
Free printable and fillable language sample analysis worksheet for speech-language pathologists. Five columns (utterance #, transcription, morpheme count, grammatical Y/N, notes), configurable row count up to 100 utterances, browser print produces a clean PDF, and an inline running summary tracks total utterances, total morphemes, and rolling MLU as you fill it in.
Open toolRelated disorders
Expressive Language Delay
Expressive language delay describes children whose spoken output lags behind age expectations while their receptive skills remain within the typical range.
PediatricReceptive Language Disorder
Receptive language disorder is a persistent impairment in understanding spoken language that is not better explained by hearing loss or another medical condition.
Pediatric · SLISpecific Language Impairment (SLI)
Specific language impairment is the older diagnostic label, now largely replaced by Developmental Language Disorder but still present in research literature.
References
- Bishop, D. V. M., Snowling, M. J., Thompson, P. A., & Greenhalgh, T. (2017). Phase 2 of CATALISE: A multinational and multidisciplinary Delphi consensus study of problems with language development. Journal of Child Psychology and Psychiatry, 58(10), 1068–1080.
- Tomblin, J. B., Records, N. L., Buckwalter, P., Zhang, X., Smith, E., & O'Brien, M. (1997). Prevalence of specific language impairment in kindergarten children. JSLHR, 40(6), 1245–1260.
- Norbury, C. F., Gooch, D., Wray, C., Baird, G., Charman, T., Simonoff, E., Vamvakas, G., & Pickles, A. (2016). The impact of nonverbal ability on prevalence and clinical presentation of language disorder. Journal of Child Psychology and Psychiatry, 57(11), 1247–1257.