Language Disorder Test: How Developmental Language Disorder Is Diagnosed

No single language disorder test diagnoses developmental language disorder (DLD). A speech-language pathologist combines standardized language tests, a sample of the child's everyday talk and reports from parents and teachers to show that language is well below age expectations, that the difficulty limits communication, learning or social participation, and that it is not explained by hearing loss, a known biomedical condition or intellectual disability. DLD is the term recommended by the CATALISE consensus (Bishop and colleagues, 2016 and 2017) for language disorder with no known differentiating cause; DSM-5-TR files the same problems under "language disorder."

This page covers where the term came from, the criteria, what an assessment contains, why nonverbal IQ no longer gates the diagnosis, and who diagnoses inside and outside school. DLD frequently co-occurs with developmental coordination disorder, its motor counterpart.

For decades the usual label was "specific language impairment" (SLI), and the word "specific" carried a requirement: language had to be poor while nonverbal ability was normal. CATALISE, a two-round Delphi consensus exercise run by Dorothy Bishop and colleagues, replaced that framework. Phase 1 drew on a panel of 59 experts from ten disciplines in six English-speaking countries; Phase 2, with 57 panelists, settled the terminology.

The Phase 2 statements define "language disorder" as language problems "likely to" endure "into middle childhood and beyond, with a significant impact on everyday social interactions or educational progress." DLD (Statement 7) is the subset with no known "differentiating condition." Those differentiating conditions (Statement 6) include brain injury, cerebral palsy, sensorineural hearing loss, genetic conditions such as Down syndrome, autism and intellectual disability; a child with one of them is described as having "language disorder associated with X." The authors note the DLD label is consistent with ICD-11, though their own definition "does not include any nonverbal ability criteria."

Co-occurring conditions are a separate category. Statement 9 lists ADHD, developmental coordination disorder, dyslexia, speech-sound problems and emotional or behavioral disorders as conditions that can sit alongside DLD without ruling it out. The overlap with motor problems is large: in one Dutch clinical sample, 32.3% of children aged 5 to 8 with SLI also met criteria for DCD.

DSM-5-TR describes language disorder as persistent difficulty acquiring and using language across modalities because of deficits in comprehension or production, such as reduced vocabulary, limited sentence structure and impaired discourse. Abilities must be substantially and quantifiably below age expectations, with functional limits on communication, social participation, academic achievement or work. Onset is in the early developmental period, and the problems must not be attributable to hearing or other sensory impairment, motor dysfunction or another medical or neurological condition, nor be better explained by intellectual disability or global developmental delay.

Two features of the CATALISE definition shape how clinicians read those criteria.

• Prognosis is part of the definition: Statement 2 ties "disorder" to problems that are likely to last. Statement 3 adds that outcome is hard to predict before age 3, and that problems affecting a range of language skills are the ones most likely to persist.

• Functional impact is required: Phase 1 Statement 11 says "a low score on a language test should be interpreted in relation to information from observation and interview; functional impact as well as test performance needs to be taken into account."

One boundary needs a single sentence here. CATALISE Statement 4 says a child whose home language differs from the school language should not be regarded as having a language disorder "unless there is evidence that the child does not have age-appropriate skills in any language," and how bilingual children are assessed is a separate subject.

CATALISE Phase 1 Statement 10 sets the frame: "Multiple sources of information should be combined in assessment, including interview/questionnaires with parents or caregivers, direct observation of the child, and standardized age-normed tests or criterion-based assessments."

• A hearing check first: The ASHA Practice Portal lists hearing screening among the first steps, "to rule out hearing loss as a possible contributing factor to language difficulties."

• Standardized language tests: Norm-referenced batteries quantify receptive and expressive language against age peers. Our page on the CELF-5 language test describes the most widely used battery and its Core Language Score, so it is not re-described here.

• A language sample: Recording and transcribing the child's spontaneous talk shows grammar and vocabulary in use. The Phase 1 paper notes that methods now exist for "standardized collection and computer-aided analysis of naturalistic language samples," which can be compared against normative data.

• Parent and teacher report: Interviews and questionnaires from adults who know the child "can pick up functional impairments that may be missed by other methods."

• Dynamic assessment: ASHA describes this "test-teach-retest" method as a way to gauge learning potential.

Convergence matters because the tests are imperfect classifiers. Spaulding, Plante and Farinella reviewed the manuals of 43 commercial child language tests. In most, children with known language impairment scored above 1.5 SD below the mean, and for 27% of tests their average fell within 1 SD of it. Only 9 manuals reported sensitivity and specificity, and only 5 of those reached 80% accuracy. CATALISE Phase 1 Statement 12 draws the conclusion: "There is no clear cut-off that distinguishes between language impairment (regardless of its cause) from the lower end of normal variation of language ability."

The old SLI definition demanded a gap between verbal and nonverbal ability, so a child with poor language and a nonverbal IQ of, say, 80 could be told they did not qualify. CATALISE Phase 1 Statement 23 rejected that rule, calling the topic "the most controversial of those we covered" while concluding that "we do not endorse the traditional view, still used in some diagnostic systems, e.g., ICD-10, of recognising language impairment only when there is a significant mismatch with nonverbal IQ." One of its stated reasons is psychometric: "discrepancy scores are so unstable that they cannot provide a reliable basis for classification or diagnosis." Phase 2 Statement 8 made it explicit: a child with a language disorder "may have a low level of nonverbal ability. This does not preclude a diagnosis of DLD." Where nonverbal ability and adaptive behavior meet criteria for intellectual disability, that becomes the primary diagnosis.

Norbury and colleagues tested the change in the first UK population study of language disorder at school entry. Of 12,398 children aged 4 to 5 in Surrey, 7,267 were screened and a stratified subsample of 529 received full assessment. The estimated prevalence of language disorder of unknown origin was 7.58%, with another 2.34% associated with intellectual disability or a known medical diagnosis. Children with low-average nonverbal IQ showed no differences from those with average nonverbal IQ in "severity of language deficit, social, emotional and behavioural problems, or educational attainment." The authors concluded that "access to specialist clinical services should not depend on NVIQ."

The professional body agrees. ASHA "does not advise using cognitive referencing as one of the criteria for admission into or discharge from speech and language services," noting that "tests of cognitive and linguistic ability often measure the same fundamental skills." That overlap is visible inside IQ tests themselves; our article on the Verbal Comprehension Index explains why a child with DLD can score low on the verbal side of a Wechsler profile for reasons that have more to do with language than with reasoning.

In clinical practice the diagnosis usually comes from a speech-language pathologist. ASHA's Practice Portal states that SLPs "play a critical role in the screening, assessment, diagnosis, and treatment of preschool and school-age children with spoken language disorders." Psychologists and developmental pediatricians also use the DSM-5-TR criteria, often within a team when other conditions are in question.

A school evaluation decides eligibility. Under federal special education law, 34 CFR 300.8(c)(11) defines "speech or language impairment" as "a communication disorder, such as stuttering, impaired articulation, a language impairment, or a voice impairment, that adversely affects a child's educational performance." The evaluation rules in 34 CFR 300.304 forbid using "any single measure or assessment as the sole criterion" for that decision. A district does not issue a DSM-5-TR diagnosis, and the educational-impact clause means a child can meet clinical criteria without qualifying for services.

DLD is common and under-recognized. Tomblin and colleagues screened 7,218 US kindergartners and estimated an SLI prevalence of 7.4%, yet the parents of only 29% of the children identified had previously been told their child had a speech or language problem. Because reading is built on spoken language, DLD and dyslexia often appear together; our article on how dyslexia is tested covers the reading side of that evaluation.

Batteries such as the CELF-5 are common, but no test diagnoses DLD by itself. A diagnosis combines test scores with a language sample, parent and teacher report, a hearing check and evidence of everyday impact.

Yes. Since CATALISE, low nonverbal ability does not preclude DLD. If the child meets criteria for intellectual disability, the language problem is described as language disorder associated with intellectual disability.

No. Speech refers to producing sounds, while language covers vocabulary, grammar, comprehension and discourse. CATALISE lists speech problems as a separate condition that can co-occur with DLD.

Usually once a child is of school age or close to it. CATALISE notes that outcome is particularly hard to predict before age 3, so younger children with limited language are often monitored before a diagnosis is made.

A language disorder test is really an evaluation that triangulates. Standardized batteries quantify language against age peers, a language sample shows it in use, parents and teachers report what happens outside the clinic, and a hearing check and history rule out other causes. The evidence explains why: most commercial tests do not reliably push children with known impairment far below the mean, and the field's own consensus says there is no clean cut-off between disorder and the low end of normal. The biggest change of the past decade concerns IQ. A normal nonverbal score is no longer required, because children with low-average nonverbal ability turned out to look the same on every outcome that matters. If you want a carefully normed estimate of reasoning ability to set beside a language assessment, you can take a full-length online IQ test and bring the report to the clinician doing the diagnostic work.

1. Bishop, D. V. M., Snowling, M. J., Thompson, P. A., Greenhalgh, T., & CATALISE consortium. (2016). CATALISE: A multinational and multidisciplinary Delphi consensus study. Identifying language impairments in children. PLOS ONE, 11(7), e0158753. doi.org

2. Bishop, D. V. M., Snowling, M. J., Thompson, P. A., Greenhalgh, T., & the CATALISE-2 consortium. (2017). Phase 2 of CATALISE: A multinational and multidisciplinary Delphi consensus study of problems with language development: Terminology. Journal of Child Psychology and Psychiatry, 58(10), 1068-1080. doi.org

3. American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.). doi.org

4. 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: Evidence from a population study. Journal of Child Psychology and Psychiatry, 57(11), 1247-1257. doi.org

5. Tomblin, J. B., Records, N. L., Buckwalter, P., Zhang, X., Smith, E., & O'Brien, M. (1997). Prevalence of specific language impairment in kindergarten children. Journal of Speech, Language, and Hearing Research, 40(6), 1245-1260. doi.org

6. Spaulding, T. J., Plante, E., & Farinella, K. A. (2006). Eligibility criteria for language impairment: Is the low end of normal always appropriate? Language, Speech, and Hearing Services in Schools, 37(1), 61-72. doi.org

7. American Speech-Language-Hearing Association. (n.d.). Spoken language disorders [Practice Portal]. asha.org

8. Flapper, B. C., & Schoemaker, M. M. (2013). Developmental coordination disorder in children with specific language impairment: Co-morbidity and impact on quality of life. Research in Developmental Disabilities, 34(2), 756-763. doi.org

9. Assistance to States for the Education of Children With Disabilities: Child with a disability, 34 C.F.R. § 300.8 (2026). law.cornell.edu

10. Assistance to States for the Education of Children With Disabilities: Evaluation procedures, 34 C.F.R. § 300.304 (2026). law.cornell.edu

Hero image: the children's area at Bonner Springs Library, Kansas, by Bonner Springs Library, licensed CC BY 2.0 (creativecommons.org/licenses/by/2.0). Via Wikimedia Commons.