Roughly half of adults in OECD countries score at or below Level 2 on the PIAAC prose literacy scale, meaning they struggle with text above a lower secondary reading level
3.1.5 Reading Level
In Plain Language
SC 3.1.5 Reading Level (Level AAA) applies when prose -- after removing proper names and titles -- demands reading ability beyond the lower secondary education level (roughly grades 7--9 in the US, ages 12--15 internationally). When it does, the page must provide either supplemental content or an alternative version that reads at or below that level[1].
The original complex text can remain. The mechanism is additive: publish a plain-language summary, an easy-read alternative, illustrations with captions, or an audio narration alongside the source, and link to it clearly.
Why It Matters
- Readability formulas (Flesch-Kincaid Grade Level, SMOG, FORCAST, Gunning Fog) score text against US grade bands. Prose that scores above grade 9 falls outside 3.1.5's lower-secondary threshold unless a conforming alternative is provided[1].
- Users with cognitive and learning disabilities, non-native readers, and users new to a technical domain comprehend lower-secondary prose at substantially higher rates than university-level text -- the barrier is the sentence structure and vocabulary, not intelligence or motivation.
- Roughly half of adults in OECD countries score at or below Level 2 on the PIAAC prose literacy scale, meaning they struggle to integrate information across paragraphs of dense text[2]. Writing government, legal, and medical content exclusively at professional-register level locks that population out.
- Supplemental visual content (diagrams, step illustrations, captioned images) and audio narration are named in the Understanding document as acceptable mechanisms -- the criterion does not demand a full text rewrite in every case[1].
Examples
Plain language summary
If your website is not accessible to people with disabilities, you may need to fix it. The law says government websites must work for everyone.
Full legal text: Pursuant to Section 508 of the Rehabilitation Act, as amended (29 U.S.C. § 794d), federal agencies shall ensure that electronic and information technology developed, procured, maintained, or used by the agency allows individuals with disabilities comparable access...
✔ Plain language summary provided before the complex legal text
<div class="summary-box">
<h3>Plain language summary</h3>
<p>If your website is not accessible to people
with disabilities, you may need to fix it.
The law says government websites must work
for everyone.</p>
</div>
<!-- Full legal text follows -->
<p>Pursuant to Section 508 of the Rehabilitation
Act, as amended...</p>Notwithstanding the provisions of the aforementioned subsection, entities subject to the jurisdiction of the regulatory authority shall effectuate compliance with the stipulated accessibility mandates within a timeframe not to exceed the prescribed statutory limitation period.
✘ Dense legal language with no plain language version -- many readers cannot understand this
<!-- FAILS: no simplified version available -->
<p>Notwithstanding the provisions of the
aforementioned subsection, entities subject
to the jurisdiction of the regulatory authority
shall effectuate compliance with the stipulated
accessibility mandates...</p>How to file a complaint:
✔ Visual step diagram supplements the written instructions
<p>How to file a complaint:</p>
<div class="steps">
<div class="step">1. Fill out the form</div>
<div class="step">2. Attach evidence</div>
<div class="step">3. Submit online</div>
</div>
<!-- Visual diagram makes the process easier
to understand for all readers -->To effectuate the initiation of the adjudicatory process, the complainant shall furnish documentary substantiation corroborating the alleged noncompliance, and subsequently transmit said materials to the designated administrative entity via the prescribed electronic submission portal.
✘ Instructions are written at a post-graduate reading level -- no simplified alternative provided
<!-- FAILS: instructions at post-graduate level
with no simpler version -->
<p>To effectuate the initiation of the
adjudicatory process, the complainant shall
furnish documentary substantiation...</p>How to Fix It
- Score the source text. Run the prose through Flesch-Kincaid Grade Level, SMOG, or Gunning Fog (Hemingway Editor, Readable.io, and most word processors expose these). Anything above roughly grade 9 triggers 3.1.5 and needs an alternative or supplement.
- Publish a plain-language summary. Place a clearly labeled summary block at the top of the complex content covering the key points in short sentences and common vocabulary. The original can remain below -- 3.1.5 is satisfied by the summary's presence, not by deleting the source[1].
- Add supplemental visuals or audio. Step diagrams, illustrated flowcharts, captioned images, and audio narration are named as acceptable supplemental content. Pair them with the dense text rather than replacing it.
- Offer an "easy read" alternative version. For policies, forms, benefits eligibility, and medical guidance, publish a separate page written at lower-secondary level and link to it with explicit navigation ("Plain Language" or "Easy Read") from the original. The linked version must cover the same information, not a marketing summary of it.
- Write the primary content at lower-secondary level when precision allows. Short sentences, active voice, and common vocabulary satisfy 3.1.5 without any alternative version. Reserve professional-register prose for contexts where legal or clinical precision requires it -- and then ship the plain-language companion.
References
- [1] W3C (2023). Understanding Success Criterion 3.1.5: Reading Level. W3C, Accessed 2026-04-07. https://www.w3.org/WAI/WCAG22/Understanding/reading-level.html ↩ ↩ ↩ ↩
- [2] OECD (2023). Survey of Adult Skills (PIAAC). OECD, Accessed 2026-04-07. https://www.oecd.org/en/about/programmes/piaac.html ↩