What is TILLS? A guide to the Test of Integrated Language and Literacy Skills
The TILLS assessment measures oral and written language in students ages 6 to 18 across 15 subtests. Learn its cut scores, dyslexia use, and limits.
Dr. Russell T. WarneChief Scientist
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TILLS, the Test of Integrated Language and Literacy Skills, is a "norm-referenced" assessment (one that compares a student's performance with national age-based norms) that measures oral and written language skills in students ages 6 through 18. Published by Brookes Publishing in 2016 and authored by Nickola Nelson, Elena Plante, Nancy Helm-Estabrooks, and Gillian Hotz, the TILLS assessment uses 15 subtests spanning listening, speaking, reading, and writing to identify language and literacy disorders such as dyslexia, to document patterns of strengths and weaknesses, and to track change over time. TILLS profiles language and literacy skills rather than intelligence, so it is a companion to cognitive testing instead of a substitute for it.
This article covers what the TILLS assessment measures, its 15 subtests, the Identification Core cut scores, and its strengths and limitations for identifying dyslexia and developmental language disorder.
What the TILLS assessment measures
Most language batteries test either spoken language or written language. TILLS was designed to do both in a single instrument. According to Brookes Publishing, the test assesses skills at two levels, the "sound/word level" (processing individual speech sounds, letters, and single words) and the "sentence/discourse level" (understanding and producing connected sentences and longer stretches of language), across the four modalities of listening, speaking, reading, and writing.
The authors describe this two-by-two framework as a quadrant model. Because every subtest was normed on the same sample of students, an examiner can directly compare a student's spoken language scores with the same student's reading and writing scores. The publisher notes that this matters because combining separate tests with separate norm groups can produce score differences that reflect the norming samples instead of the student's skills.
The test is individually administered by speech-language pathologists, special educators, reading specialists, and other professionals trained in standardized test administration. Brookes Publishing reports that all 15 subtests can be given in one 70 to 90 minute session or two 45 minute sessions, and each subtest produces a "standard score" with a mean of 10 and a standard deviation of 3.
The 15 subtests of TILLS
Brookes Publishing lists the 15 subtests along with the task each one presents to the student. In administration order, they are:
• 1. Vocabulary Awareness: the student finds a pair of semantically related words in a set of three, then switches sets to find a second pairing.
• 2. Phonemic Awareness: the student isolates and deletes individual speech sounds ("phonemes") from the beginning of real and nonsense words.
• 3. Story Retelling: the student listens to an age-appropriate story and retells it.
• 4. Nonword Repetition: the student repeats recorded nonsense words, which taps speech perception and phonological memory.
• 5. Nonword Spelling: the student spells recorded nonsense words using conventional letter patterns.
• 6. Listening Comprehension: the student hears short stories and answers yes, no, or maybe questions that require inference.
• 7. Reading Comprehension: the student reads similar short stories and answers the same style of questions, in parallel with the listening version.
• 8. Following Directions: the student carries out spoken directions of increasing length, which requires holding instructions in short-term memory.
• 9. Delayed Story Retelling: the student retells the story from subtest 3 after 15 to 20 minutes, measuring retention of narrative information.
• 10. Nonword Reading: the student reads printed nonsense words aloud, isolating "decoding" (sounding out unfamiliar words) from memorized sight words.
• 11. Reading Fluency: the student reads a series of connected facts aloud while the examiner counts words read automatically.
• 12. Written Expression: the student rewrites a set of choppy story facts into more mature prose, yielding separate discourse, sentence, and word scores.
• 13. Social Communication: the student says what a character might say in a social scene, testing pragmatic language.
• 14. Digit Span Forward: the student repeats number sequences verbatim, a short-term verbal memory measure.
• 15. Digit Span Backward: the student repeats number sequences in reverse order, a verbal working memory measure.
Digit span tasks also appear on IQ tests such as the WISC-V, yet in TILLS they serve a narrower purpose. The authors state that these memory subtests help examiners interpret language performance; they do not turn TILLS into a cognitive battery.
Identification Core scores and cut scores
TILLS was built for three purposes: identifying language and literacy disorders, profiling relative strengths and weaknesses, and tracking change over time. The first purpose runs through a composite called the "Identification Core," a sum of standard scores from a small set of subtests chosen for each age band because they best separated students with known disorders from typically developing peers.
The technical manual reports the composition and performance of the Identification Core for three age bands:
• Ages 6-7: Vocabulary Awareness, Phonemic Awareness, and Nonword Repetition, with a cut score of 24, sensitivity of 84 percent, and specificity of 84 percent.
• Ages 8-11: Vocabulary Awareness, Nonword Spelling, Nonword Reading, and the Written Expression discourse score, with a cut score of 34, sensitivity of 88 percent, and specificity of 85 percent.
• Ages 12-18: Phonemic Awareness, Nonword Spelling, Reading Comprehension, Reading Fluency, and the Written Expression word score, with a cut score of 42, sensitivity of 86 percent, and specificity of 90 percent.
"Sensitivity" is the percentage of students with a disorder whom the test correctly flags, and "specificity" is the percentage of typically developing students it correctly clears. An Identification Core score below the cut score for the student's age suggests a language or literacy disorder; a score at or above it suggests the disorder is absent. Across individual ages in the manual's tables, sensitivity ranges from 81 to 97 percent and specificity from 81 to 100 percent. The Identification Core subtests alone take about 25 to 45 minutes, and the publisher reports that TILLS can be re-administered after a minimum of six months for progress monitoring.
The norms come from a standardization program involving more than 1,200 students, and the technical manual reports validation comparisons against 279 students previously diagnosed with language or literacy disorders, plus matched-group studies of students with autism spectrum disorder, hearing loss, and intellectual disability.
TILLS for dyslexia and developmental language disorder
Because TILLS covers oral and written skills at both levels of language, it lends itself to the uneven profiles that define many learning disorders. In an interview published by Brookes, the authors explain that a dyslexia diagnosis would be consistent with a pattern of low TILLS scores in sound and word structure knowledge, for example weak nonword reading, nonword spelling, and phonemic awareness alongside stronger discourse-level listening. A student with developmental language disorder tends to show a different pattern, with depressed scores across oral language subtests as well.
This profile-based approach also avoids "cognitive referencing," the older practice of requiring a gap between IQ and language scores before providing services. TILLS scores stand on their own norms, which is one reason the test pairs naturally with, and does not duplicate, dedicated instruments such as the CELF-5 for oral language, the CTOPP-2 for phonological processing, and the GORT-5 for oral reading fluency. Where those tests each examine one domain in depth, TILLS surveys the whole language-literacy system in one sitting with one norm group.
Strengths and limitations
The TILLS assessment has genuine strengths. The authors state that it provides sensitivity and specificity evidence for every age at which it is normed, which remains uncommon among language tests. The single normative sample makes cross-domain comparisons legitimate, and the quadrant framework gives teams a clear way to describe uneven profiles.
It also has limits worth naming. The cut scores apply to the ages the test was normed on, and research shows the boundaries matter. A 2024 study in the American Journal of Speech-Language Pathology by Choi-Tucci, White, and Plante found that the recommended cut score of 42 for ages 12 to 18 underidentified language disorders when the test was extended to 59 college students ages 18 to 23; an adjusted cut score of 51 was needed to bring sensitivity and specificity back above 80 percent. Sensitivity and specificity in the mid-80s to low-90s also mean that some students will be missed and some misflagged, so scores should be interpreted alongside history, observation, and other measures. And because TILLS does not measure nonverbal reasoning or broader cognition, a full evaluation for a learning disability usually still includes a cognitive measure.
Language testing and cognitive testing answer different questions
TILLS tells a team how a student's listening, speaking, reading, and writing compare with peers, and where the profile tilts. It does not estimate intelligence, and an IQ test does not diagnose a language or literacy disorder. The two kinds of information complement each other, which is why comprehensive evaluations typically include both.
For adults who want a rigorous picture of their own cognitive abilities, the RIOT IQ test (Reasoning and Intelligence Online Test) was developed by RIOT IQ with psychometrician Dr. Russell T. Warne for ages 18 and up. It includes 15 subtests across six cognitive indices (verbal reasoning, fluid reasoning, spatial ability, working memory, processing speed, and reaction time), takes about 52 minutes, and reports scores on the familiar mean-100, standard-deviation-15 IQ scale. Like any online measure, it does not replace an individually administered diagnostic evaluation. It does provide a normed profile of cognitive strengths in the same spirit of profile-based interpretation that makes TILLS useful.
Frequently asked questions
Is TILLS an IQ test?
No. TILLS measures oral and written language and literacy skills, and its digit span subtests measure verbal memory to aid interpretation. It produces no IQ score and is designed to profile language and literacy rather than intelligence.
What ages is the TILLS assessment for?
TILLS is normed for students ages 6;0 through 18;11. A 2024 study found the published cut score underidentified disorders in college students, so results beyond age 18 require adjusted interpretation.
How long does TILLS take to administer?
Brookes Publishing reports all 15 subtests take one 70 to 90 minute session or two 45 minute sessions. The Identification Core subtests alone take about 25 to 45 minutes.
Can TILLS diagnose dyslexia?
TILLS is designed to help qualified professionals identify language and literacy disorders, including dyslexia, as part of a comprehensive evaluation. Low scores in sound and word structure subtests such as Nonword Reading and Nonword Spelling are consistent with dyslexia.
Who can administer TILLS?
Speech-language pathologists, special educators, reading specialists, learning disability specialists, neuropsychologists, educational psychologists, and other professionals trained in individualized standardized testing.
What is a TILLS Identification Core score?
It is the sum of standard scores from an age-specific set of subtests. Scores below the age-based cut score (24 for ages 6-7, 34 for ages 8-11, 42 for ages 12-18) suggest a language or literacy disorder.
References
1. Brookes Publishing Co. (n.d.). TILLS (Test of Integrated Language and Literacy Skills). brookespublishing.com
2. Brookes Publishing Co. (n.d.). The 15 subtests of the Test of Integrated Language and Literacy Skills (TILLS). brookespublishing.com
3. Nelson, N. W., Plante, E., Helm-Estabrooks, N., & Hotz, G. (2016). Test of Integrated Language and Literacy Skills (TILLS) technical manual (excerpt). Paul H. Brookes Publishing Co. tillstest.com
4. Brookes Publishing Co. (n.d.). About TILLS: Literacy and language assessment tool. tillstest.com
5. Brookes Publishing Co. (n.d.). Literacy and language assessment FAQs. tillstest.com
6. Choi-Tucci, A., White, M., & Plante, E. (2024). Determining the diagnostic accuracy of the Test of Integrated Language and Literacy Skills for college students. American Journal of Speech-Language Pathology, 33(2), 1051-1058. pubmed.ncbi.nlm.nih.gov
7. Brookes Publishing Co. (n.d.). TILLS: Discover a better way to assess language and literacy skills (author interview). brookespublishing.com
Photo by WOKANDAPIX, via Wikimedia Commons (CC0)
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