"Dyslexia is a specific learning disability characterized by difficulties in word reading and/or spelling that involve accuracy, speed, or both and vary depending on the orthography. These difficulties occur along a continuum of severity and persist even with instruction that is effective for the individual's peers. The causes of dyslexia are complex and involve combinations of genetic, neurobiological, and environmental influences that interact throughout development. Underlying difficulties with phonological and morphological processing are common but not universal, and early oral language weaknesses often foreshadow literacy challenges. Secondary consequences include reading comprehension problems and reduced reading and writing experience that can impede growth in language, knowledge, written expression, and overall academic achievement. Psychological well-being and employment opportunities also may be affected. Although identification and targeted instruction are important at any age, language and literacy support before and during the early years of education is particularly effective."
Source: International Dyslexia Association (2025). 2025 Dyslexia Definition Project. dyslexiaida.org
- Causes: "Neurobiological in origin" → now reflects complex interactions among genetic, neurobiological, and environmental influences
- Continuum: Dyslexia occurs along a continuum of severity; the "unexpected relative to IQ" framing is removed — IQ discrepancy is not a requirement
- Underlying processes: Morphological processing added alongside phonological processing; both are common but not universal
- Secondary consequences: Expanded to include writing experience, psychological well-being, and employment opportunities
- Early intervention: Explicitly emphasized for the first time in a formal IDA definition
All three questions must be addressed in an evaluation where dyslexia is suspected (Texas Dyslexia Handbook, 2024, p. 43). Note: This framework reflects the 2024 handbook's language, which predates the IDA 2025 definition update. It remains operative Texas policy.
• Difficulty with accurate and/or fluent word recognition
• Poor decoding and/or poor spelling
• Secondary consequences may include difficulties in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge
Do these difficulties typically result from a deficit in the phonological component of language — including phonological awareness, phonological memory, and/or rapid automatized naming?
Are these difficulties unexpected for the student's age in relation to the student's other abilities and the provision of effective classroom instruction?
Source: Texas Dyslexia Handbook pp. 43–44 (2024); IDA Definition (2025)
Common misconceptions complicate identification. The evaluator should be prepared to address these in the FIE and in ARD conversations.
Source: IDA Definition (2025); Texas Dyslexia Handbook (2024)
What it is: The ability to detect, manipulate, and reflect on the sound structure of language — independent of meaning. The bedrock skill for decoding and spelling.
Key skills (developmental order):
- Rhyme awareness and production
- Syllable segmentation and blending
- Onset-rime manipulation
- Phoneme isolation, segmentation, blending
- Phoneme deletion, substitution, reversal
Assessment tools:
What it is: The ability to temporarily hold phonological information in working memory — essential for blending phonemes while decoding multisyllabic words and for retaining newly learned letter-sound associations.
Observable indicators:
- Difficulty repeating nonsense words
- Loses the beginning of a word while decoding the end
- Difficulty retaining new vocabulary or names
- Low digit span performance
Assessment tools:
What it is: The speed at which familiar symbols — letters, digits, colors, objects — can be retrieved from long-term memory and named in sequence. RAN is distinct from PA and strongly predicts reading fluency.
Observable indicators:
- Slow, labored oral reading despite knowing words individually
- Word retrieval difficulties in conversation
- Slow letter and digit naming on timed tasks
- Reading that does not become automatic despite repeated practice
Assessment tools:
Orthographic mapping (Ehri, 2014) is the process by which a reader forms a permanent, instant-access memory for a word's spelling, pronunciation, and meaning. It is how sight words are built — not through rote memorization, but through the systematic connection of phonemes to graphemes.
For orthographic mapping to occur, the reader must:
- Segment the spoken word into phonemes (phonological awareness)
- Know the grapheme-phoneme correspondences (alphabetic knowledge)
- Bond the phonological and orthographic representations in long-term memory
Students with dyslexia have weak phonological representations — the "pegs" onto which orthographic knowledge is hung are unstable. This is why:
- Sight words must be re-taught repeatedly without retention
- Decoding of novel words is slow and error-prone
- Reading fluency lags far behind listening comprehension
- Spelling is inconsistent even for words previously mastered
Source: Ehri (2014); Kilpatrick (2015); Texas Dyslexia Handbook (2024)
The Simple View of Reading (Gough & Tunmer, 1986) defines reading comprehension as the product of two component skills:
Reading Comprehension = Decoding × Language Comprehension
This framework is essential for differential eligibility reasoning:
| Profile | Decoding | Lang. Comp. | Reading Comp. |
|---|---|---|---|
| Dyslexia | Weak | Adequate–Strong | Impaired (word-level bottleneck) |
| DLD/SLI | Adequate | Weak | Impaired (language bottleneck) |
| Mixed (Dyslexia + DLD) | Weak | Weak | Severely impaired |
| Hyperlexia | Strong | Weak | Impaired (comprehension bottleneck) |
Source: Gough & Tunmer (1986); Hoover & Gough (1990); Texas Dyslexia Handbook (2024)
Tier 1 — Universal: All students receive Structured Literacy (sometimes called "Orton-Gillingham-based" or "Science of Reading-aligned") instruction in foundational reading skills, delivered with high fidelity and explicitness:
- Phonological Awareness (rhyme, syllables, phonemes) — taught explicitly, 10–15 min/day
- Phonics (sound-symbol relationships, decoding) — systematic, cumulative, multisensory
- Fluency (accuracy → automaticity → expression) — repeated reading, decodable texts, timed practice
- Vocabulary (word meanings) — taught in context, through multiple exposures, with morphological awareness
- Comprehension (understanding text) — explicit strategies, monitoring, discussion
Tier 2 — Targeted for non-responders: Students who do not gain adequate decoding and fluency skills in Tier 1 (despite 8–12 weeks of high-quality universal instruction) receive accelerated, intensive Structured Literacy intervention — same components (phonological awareness, phonics, fluency) but with more time, smaller group size, and faster pacing.
Why students move to Tier 3: Students who receive high-quality Structured Literacy instruction in Tier 1 and Tier 2 but continue to struggle with decoding and fluency despite adequate time, intensity, and instruction quality are referred for comprehensive evaluation.
What the evaluation looks for: Persistent difficulties in phonological processing (CTOPP PA, RAN scores ≤15th %ile) that are inconsistent with general cognitive ability and consistent with the observed decoding/fluency deficits. This pattern suggests dyslexia, not simply "slow reading."
Benchmark CBMs (universal screening): All students progress-monitored on DIBELS Next or similar CBM quarterly or biannually.
- K–1: PSF (Phoneme Segmentation Fluency), NWF (Nonsense Word Fluency)
- 1–3: NWF, ORF (Oral Reading Fluency), DAZE (Maze for comprehension)
- 3+: ORF, DAZE
For Tier 2 intervention: Weekly or bi-weekly CBM progress monitoring on the target skill (e.g., NWF if intervention targets decoding; ORF if fluency is primary).
For FIE documentation: Include 6–12 weeks of progress monitoring data showing:
- Initial baseline (pre-intervention CBM score)
- Intervention record (frequency, duration, program name — e.g., Orton-Gillingham, Wilson Fundations, Sounds of Reading)
- Progress monitoring trend (weekly CBM data, plotted over time, compared to expected growth slope)
- Response to intervention conclusion (e.g., "Minimal progress despite 10 weeks of intensive phonics intervention; insufficient response indicated")).
Phonological Processing:
Word-Level Reading:
Reading Fluency:
Spelling:
Oral Reading Sample: Have the student read a grade-level passage aloud. Record error types: substitutions, omissions, insertions, self-corrections. Phonetically implausible errors (e.g., "horse" for "house") indicate phonological decoding failure. Phonetically plausible errors (e.g., "hous" for "house") suggest PA awareness but incomplete orthographic mapping.
Decoding Probe: Present 10–15 pseudowords of increasing length (CVC → CCVCC → multisyllabic). Slow, effortful, or phonologically inaccurate decoding is a direct measure of phoneme-grapheme mapping failure — not a reading comprehension issue.
Spelling Error Analysis: Collect unedited writing samples. Classify errors:
• Phonologically implausible (e.g., "tge" for "the") → PA deficit
• Phonologically plausible (e.g., "duz" for "does") → orthographic mapping weakness, phonology intact
• Omission of phonemes (e.g., "wnt" for "went") → phoneme segmentation deficit
Intervention Response History: Document Tier 2/3 interventions, fidelity, duration, and progress monitoring data. Resistance to evidence-based structured literacy intervention supports the "unexpected" and "inadequate instruction excluded" prongs.
The most clinically powerful indicator of dyslexia — versus a broader language-based disability — is the gap between oral language ability and written word recognition. Collect and compare:
- Oral vocabulary / listening comprehension — typically adequate to strong in dyslexia
- Verbal reasoning / oral expression — typically intact
- Word reading / decoding — significantly below oral language level
- Reading comprehension — impaired through word-level bottleneck, not language itself
Framework: Gough & Tunmer (1986); WJ-V OL Cluster; WIAT-IV Listening Comprehension
At reevaluation, scores at or above standard score 85 (16th percentile) are not evidence that dyslexia has resolved. They are evidence that structured literacy intervention has been effective. The underlying phonological processing profile and the student's need for ongoing accommodations remain.
Apply the persistence rule when:
- Prior FIE documented dyslexia eligibility and
- Reeval scores are ≥85 in word reading, decoding, or reading fluency
Document in the FIE:
- The student received intensive structured literacy intervention consistent with the original eligibility area
- Score improvement is attributed to intervention success — not to the absence of a disability
- The student continues to require accommodations (extended time, audiobooks, text-to-speech) to access grade-level curriculum without the disability impacting educational performance
- Discontinuing eligibility would remove supports that are sustaining current functioning
Source: Texas Dyslexia Handbook (2024); HB 3928 FAQ (TEA, 2023); IDEA 2004 §614(c)
Estimates suggest that 25–40% of students with dyslexia also meet criteria for ADHD, and vice versa. Co-occurrence is common enough that evaluators should routinely consider both when either is suspected. Despite the overlap, the mechanisms are distinct:
| Dimension | Dyslexia | OHI — ADHD (reading impact) |
|---|---|---|
| Primary mechanism | Phonological processing deficit — word recognition and decoding specific | Attention, executive self-regulation — access and sustained effort |
| Reading across conditions | Consistently weak regardless of interest level, reading support, or environmental structure | Variable — improves with high-interest text, brief sessions, movement breaks, and structure |
| Decoding accuracy | Poor even on brief, single-word tasks in a quiet, distraction-free environment | Decoding accuracy often adequate; breakdowns occur under sustained load |
| Fluency pattern | Slow due to word-level processing failure — phonological bottleneck | Slow due to inconsistent attention deployment — not word-level failure |
| Phonological processing | Deficits evident on direct PA, PM, and RAN measures | Phonological processing typically intact; reading fluency may be inconsistent |
| Dual eligibility appropriate? | Yes — when both conditions independently contribute to educational need. Document each disability's independent contribution. Both SLD (dyslexia) + OHI-ADHD may be appropriate when phonological deficits and attention/EF deficits are each separately limiting educational performance. | |
Sources: Willcutt & Pennington (2000); Shaywitz, S. E., & Shaywitz, B. A. (2020). Overcoming Dyslexia (2nd ed.). Knopf; TEA SLD Guidance (2025)
Dyslexia and DLD (also documented as SLI or language-based learning disability) are the most commonly confused profiles in reading evaluations. Both can produce low reading comprehension — but through entirely different mechanisms, with different eligibility implications and different instructional needs.
| Dimension | Dyslexia | DLD / SLI | Mixed (Dyslexia + DLD) |
|---|---|---|---|
| SVR bottleneck | Decoding weak; language comprehension adequate–strong | Decoding adequate; language comprehension weak | Both decoding and language comprehension weak |
| Word reading / decoding | Significantly below average; pseudoword decoding especially poor | Often average or near-average; may decode words without understanding them | Below average on both word reading and comprehension |
| Reading comprehension | Impaired through word-level bottleneck — improves substantially when text is read aloud | Impaired even when text is read aloud — the comprehension deficit is in the language system, not the decoding system | Impaired in both conditions |
| Listening comprehension | Intact — strong relative strength; student understands what is heard | Weak — vocabulary, syntax, inferencing, and/or narrative comprehension all affected | Weak, though may be stronger than reading comprehension |
| Oral vocabulary / verbal reasoning | Typically age-appropriate; may be a relative strength | Below average; limited vocabulary depth and breadth; reduced verbal reasoning | Below average in both areas |
| Phonological processing | PA, PM, and/or RAN deficits evident on direct testing | Phonological processing may be intact or mildly low; not the primary profile | PA/PM deficits present alongside language deficits |
| Spelling pattern | Phonologically implausible or phonologically plausible errors — phonology-based breakdown | May spell phonetically but use words incorrectly; semantic and morphological errors | Mixed error patterns |
| Key clinical move | Read the passage aloud — if reading comprehension improves significantly, the bottleneck is decoding, not language | Read the passage aloud — if comprehension remains poor even when text is read aloud, the bottleneck is language | Both conditions apply independently |
| Eligibility pathway | SLD — Basic Reading Skills / Reading Fluency (dyslexia) | Speech-Language Impairment (SLI) — collaborative determination with SLP; may also qualify as SLD-Reading Comprehension | Dual eligibility: SLD (dyslexia) + SLI — each documented separately |
Framework: Gough & Tunmer (1986); Catts et al. (2006); Tunmer & Hoover (2019); Stanley, TEDA 2026
Use when reeval reading scores are at or above SS 85 but prior eligibility was dyslexia and the student received structured literacy intervention. Adapt as needed.
"[Student]'s current word reading and decoding scores fall within the average range (SS [X], [X]th percentile). This represents meaningful growth from the [prior year] evaluation, during which scores were in the [below average/low] range. [Student] has received [intervention name] — an evidence-based structured literacy program — with documented fidelity for [duration]. Current scores reflect the educational impact of that intervention, not the absence of a learning disability."
"[Student] continues to demonstrate characteristics consistent with dyslexia, including [e.g., slower reading rate on timed tasks / continued phonological processing weaknesses / spelling errors consistent with orthographic mapping difficulty]. [Student]'s current academic functioning is being sustained by the accommodations and supports currently in place. Removing eligibility at this time would discontinue access to supports that are directly enabling [his/her/their] present level of performance."
"The evaluation team concludes that [Student] continues to meet eligibility criteria for Specific Learning Disability in the area of Basic Reading Skills consistent with characteristics of dyslexia. Pursuant to HB 3928 (88th Leg., 2023) and the Texas Dyslexia Handbook (2024), score normalization in the context of intensive structured literacy intervention does not constitute resolution of the disability."
Use when reeval scores remain in the below-average or low range and dyslexia pattern is persistent. Adapt as needed.
"[Student]'s reading profile at reevaluation remains consistent with the pattern identified in [prior year]. Word reading (SS [X]), pseudoword decoding (SS [X]), and reading fluency (SS [X]) continue to fall in the [below average/low] range. Phonological processing measures [describe: e.g., CTOPP-2 PA Composite SS [X], RAN Composite SS [X]] remain below age expectations, indicating that the underlying phonological processing deficit has not resolved."
"[Student] has received [intervention] at [Tier 2/3] for [duration]. Progress monitoring data indicate [describe: e.g., growth at a rate below grade-level peers / inconsistent response / growth in some areas but not others]. This pattern of limited response to evidence-based structured literacy instruction is consistent with a significant phonological processing deficit and further supports the presence of a specific learning disability in reading."
"[Student]'s reading difficulties continue to adversely affect educational performance across settings, including [e.g., access to grade-level text in science and social studies / timed reading and writing tasks / independent completion of reading assignments]. [Student] requires continued specially designed instruction and accommodations to access the general education curriculum."
Parents and general education staff sometimes question continued eligibility when scores have improved. These talking points can support the ARD conversation:
- "Think of it like glasses." A student who needs glasses to see 20/20 does not have their vision disorder resolved — they have it corrected. Removing the glasses removes the correction. Structured literacy, extended time, and text-to-speech are [Student]'s "glasses."
- "The intervention is working — that's the point." Score improvement is the goal of the intervention. It does not mean the disability is gone; it means the supports are doing their job.
- "Texas law specifically addresses this." HB 3928 (2023) clarified that students identified with dyslexia can continue to receive services under SLD even when scores normalize, as long as the need for supports continues.
- "What would happen without the supports?" If the student would struggle to access grade-level work without accommodations, the adverse educational effect is still present — it is being managed, not eliminated.
A peer-reviewed analysis of Texas PEIMS data across 839 school districts (Simmons, Shin & Hart, 2024, Texas Education Review) documents the impact of federal corrective action and state legislation on dyslexia identification rates:
- 2016–17 baseline: 4.10% of total Texas student enrollment identified with dyslexia statewide.
- 2022–23: 7.03% — a 3-percentage-point increase representing approximately 142,130 additional students across Texas.
- Primary driver: The 2018 OSEP Corrective Action to TEA (finding that TEA failed to ensure all students with disabilities were identified and evaluated) is identified as the single strongest catalyst for the identification increase.
- Most conservative national estimate of true dyslexia prevalence is 5% (Odegard et al., 2020) — Texas is now approaching and in many districts exceeding this threshold.
The Simmons et al. (2024) analysis broke down identification trends by NCES district locale — revealing important patterns relevant to suburban Texas diagnosticians:
- Rural districts had the highest baseline identification in 2016–17 (4.78%) but the slowest rate of increase (+1.5% over 7 years). Rural districts had historically served more students with disabilities before the 8.5% enrollment cap was enacted (2004).
- Suburban districts showed the greatest rate of increase — 2.77 percentage points over the study period — more than any other locale type. Suburban districts like those in the Williamson County area were likely among the lowest identifiers pre-corrective action and are "catching up."
- City districts increased from 2.80% to 5.29%; town districts from 3.88% to 6.62%; rural from 4.78% to 7.95%.
- Urban (city + suburban combined) increased 3% vs. rural (town + rural combined) increase of 2% — suburban growth is driving the statewide trend.
Source: Simmons, M., Shin, M., & Hart, S. (2024). Dyslexia identification: Texas legislative trends in prevalence rate of students by school district locale. Texas Education Review, 12(2), 6–24.
Dyslexia is fundamentally a Word Recognition strand disorder in Scarborough's Reading Rope. The language comprehension strands (top half) are typically intact — it is the bottom half that breaks down. Understanding which specific strand is impaired drives both assessment battery selection and intervention targeting.
- Phonological Awareness — PA deficit is the primary mechanism; the core phonological processing disorder that prevents reliable phoneme-grapheme mapping
- Decoding (Phonics) — the output of PA failure; phonologically inaccurate decoding attempts on unfamiliar words
- Sight Word Recognition (Orthographic Mapping) — words do not become instantly recognizable because the phonological "pegs" for orthographic bonding are unstable (Ehri, 2005; Kilpatrick, 2015)
- Vocabulary — usually at or above grade level; drives the "unexpected" criterion
- Language Structures — sentence-level comprehension typically intact
- Verbal Reasoning — Gf reasoning is typically strong; often the clearest strength in the profile
- Background Knowledge — may be secondarily limited due to reduced reading experience, not a primary deficit
→ View the full Learning Ropes page ↗ for the complete Reading Rope strand model with CHC tags, cross-rope connections, and the Simple View callout box.
Texas Policy — Dyslexia & SLD-Basic Reading / Reading Fluency
Dyslexia is identified within the SLD category under Texas TAC §89.1040 and TEC §38.003. Students are reported under the SLD eligibility category, with dyslexia named as the specific pattern of need — it does not require co-occurring deficits in other SLD areas. The Texas Dyslexia Handbook (2024) is the primary policy document governing identification; all public schools are required to follow it.
HB 3928 (88th Leg., 2023) clarified that dyslexia may be listed as the specific learning disability identified — it does not need to be subsumed under a broader SLD label. This is consistent with the OSERS Dear Colleague Letter (October 23, 2015), which clarified that nothing in IDEA prohibits the use of the terms dyslexia, dysgraphia, and dyscalculia in evaluation reports, eligibility determinations, and IEP documents.
TEC §38.003 (as amended, 89th Leg., 2025): HB 2 and SB 568 (89th Texas Legislature, Regular Session, 2025) amended TEC §38.003. The SBOE is actively revising the Dyslexia Handbook to align with these statutory changes. Until a new handbook is formally adopted, the 2024 Handbook remains operative policy. Practitioners should monitor TEA and SBOE communications for the updated handbook release.
The Texas Dyslexia Handbook (2024) requires that evaluations include assessment of the phonological component of language (PA, PM, RAN) and word-level reading (word recognition, decoding, spelling). Evaluation teams must also consider data from K–1 universal screening, classroom-based observations, intervention response history, and parent/teacher input. Note: the 2024 handbook references the IDA 2002 definition; the IDA updated its definition in October 2025 (see callout above).
Universal Screening: Under TEC §28.006, all students in kindergarten and first grade must be screened for reading difficulties, including characteristics of dyslexia, using a TEA-approved screening instrument. Screening data must be included in the FIE for students in these grades when dyslexia is the area of concern.
Bilingual/EB considerations: Dyslexia can be identified in English learners when the phonological processing deficit is present in the student's dominant language and cannot be attributed solely to normal second-language acquisition. Cross-linguistic phonological assessment using the Batería IV COG or Spanish CTOPP equivalent is recommended when Spanish is the dominant language.
Sources: Texas Dyslexia Handbook (2024); TEC §38.003 (as amended by HB 2 & SB 568, 89th Leg., 2025); TEC §28.006; TAC §89.1040; HB 3928 FAQ (TEA, 2023); OSERS Dear Colleague Letter (October 23, 2015); TEA Guidance for the Comprehensive Evaluation of SLD (January 2025); IDA Definition of Dyslexia (2025)