Question: A few days ago we were talking about SLD eligibility. The last three schools I worked at (over ~8 years) all used the 22-point discrepancy. I’ve heard that’s outdated, and when I looked up the rules it felt vague.
What criteria are you using now, and which tests support it? I’m in Missouri, but I’d love to hear how other places do it too.

Answer: Short answer: The old “22-point gap” (≈1.5 SD) is the classic severe discrepancy method. It’s not required by IDEA. Districts may identify SLD using:

RTI/MTSS progress (insufficient progress despite good interventions), or

Pattern of Strengths & Weaknesses (PSW), or

Severe discrepancy if state/district policy still permits it.
IDEA lets states/districts use RTI and PSW; many have moved away from “gap-only.”

Missouri practice (what we see day-to-day): MO supports both RTI and PSW. Many LEAs still operationalize PSW with a ~1.5 SD (~22-point) ability–achievement gap for the area of concern—but that’s one option, not the only route. Plenty of MO districts also qualify via RTI with progress-monitoring data.

What data/assessments teams typically use

RTI/MTSS route: universal screening + progress-monitoring CBM graphs (e.g., Acadience/DIBELS, AIMSweb, easyCBM) showing the student’s trend below the aimline despite intensified, research-based interventions (document minutes, group size, fidelity). Add normed achievement tests in the area(s) of concern.

PSW route: a coherent profile—strengths alongside specific weaknesses consistent with SLD. Often includes:

Ability: WISC-V / KABC-II / DAS-II indexes

Processing: CTOPP-2 (phonological), RAN/RAS, working memory/processing speed

Achievement: WIAT-4 / WJ-IV ACH / KTEA-3 (use clusters aligned to referral: Basic Reading, Reading Fluency, Reading Comp, Written Expression, Math Calculation/Problem Solving)

Some districts still add a ≥1.5 SD ability–achievement discrepancy table as supporting evidence.

Discrepancy (legacy) route: a ~22-point IQ–achievement gap. If used, teams should corroborate with processing, achievement, classroom data, observations, and rule-outs (instruction, attendance, vision/hearing).

Why people call the 22-point method “outdated”
In 2006, federal regs explicitly allowed RTI and PSW and stopped requiring severe discrepancy. Many states shifted toward response to instruction and pattern-based decisions rather than a single gap score.

Practical tip to ask your LEA
“Which SLD pathways does our district use (RTI, PSW, discrepancy)? Do you have written procedures—what tests/cut scores? If RTI is used, can we review intervention logs, progress-monitoring graphs, and fidelity checks?”

References (rules & guidance)

IDEA SLD criteria: 34 C.F.R. §300.309 (inadequate achievement + insufficient progress under RTI or PSW; evaluation components).

States can’t require discrepancy; must permit RTI: 34 C.F.R. §300.307.

Typical measures used by teams: publisher manuals and state guidance commonly reference WISC-V/KABC-II/DAS-II; CTOPP-2/RAN-RAS; WIAT-4/WJ-IV ACH/KTEA-3; plus CBM tools (Acadience/DIBELS, AIMSweb, easyCBM).