WCAG 2.0 Explained: What It Means for Website Accessibility

WCAG 2.0, the second version of the Web Content Accessibility Guidelines, is a technical standard published by the World Wide Web Consortium (W3C). It defines how to make web content accessible to people with disabilities. W3C released it as a Recommendation in December 2008, and it served as the main benchmark for web accessibility for roughly a decade.

WCAG 2.1 and 2.2 have since become the preferred references, but WCAG 2.0 still matters. Federal law continues to name it, and many existing agreements and audit reports are built on it. This article covers what the standard is, where it is still referenced in law, what it requires, and whether it is still enough for compliance.

What Is WCAG 2.0?

The WCAG 2.0 accessibility guidelines are organized around four principles, a set of testable success criteria, and three conformance levels.

A Brief History: From 2008 to ISO Standard

W3C published WCAG 2.0 on December 11, 2008, replacing WCAG 1.0 from 1999. Unlike its predecessor, it was written to be technology-neutral and testable rather than tied to specific HTML techniques. In 2012, it was recognized as ISO/IEC 40500, giving it standing as an international standard.

The Four Principles: Perceivable, Operable, Understandable, Robust

Every WCAG 2.0 success criterion falls under one of four principles:

• Perceivable: information must be presentable in ways users can perceive, such as text alternatives for images and captions for video.
• Operable: all functionality must work through a keyboard and give users enough time to complete tasks.
• Understandable: content and interface behavior must be readable and predictable.
• Robust: content must work reliably with current and future assistive technologies.

Conformance Levels A, AA, and AAA

WCAG 2.0 contains 61 success criteria. Level A covers the most basic requirements, Level AA addresses the most common barriers, and Level AAA is the most demanding. WCAG 2.0 Level AA means meeting every Level A and Level AA criterion, 38 in total. Because Level AAA cannot be met for all content, AA is the working benchmark in law and practice, and WCAG 2.0 AA standards are what most compliance requirements reference.

Where WCAG 2.0 Is Still Referenced in Law

WCAG 2.0 is no longer the newest standard, but several legal frameworks still point to it.

Section 508

The U.S. Access Board’s 2017 refresh incorporates WCAG 2.0 Level A and AA by reference. For federal agencies and the vendors that sell to them, WCAG 2.0 Level AA remains the formal technical standard for web content. See our Section 508 guide for how this fits into procurement and VPAT requirements.

Older Settlements and Consent Decrees

Many ADA settlements and consent decrees signed before the DOJ’s 2024 Title II rule name WCAG 2.0 AA as the target. Organizations under these agreements may still be measured against it until the agreement ends or is amended.

What WCAG 2.0 Requires for Websites

A WCAG 2.0 AA checklist comes down to a few core requirements, each tied to a specific success criterion:

• Text alternatives (1.1.1): every informative image needs descriptive alt text.
• Captions (1.2.2): prerecorded video with audio needs synchronized captions.
• Color contrast (1.4.3): text needs a contrast ratio of at least 4.5:1, or 3:1 for large text.
• Keyboard access (2.1.1): all functionality must be operable without a mouse.
• Page titles (2.4.2): each page needs a title that describes its purpose.
• Labels and instructions (3.3.2): form fields need clear labels.
• Name, role, value (4.1.2): interactive elements must be identifiable by assistive technology.

Meeting these criteria across a full site takes a manual website accessibility audit, since automated scans catch only part of them.

WCAG 2.0 vs. WCAG 2.1 and 2.2

WCAG 2.1, released in 2018, keeps every WCAG 2.0 criterion and adds 17 more, focused on mobile accessibility, low vision, and cognitive disabilities. WCAG 2.2, released in 2023, adds nine more criteria and removes one: 4.1.1 Parsing, which W3C retired because browsers and assistive technology now handle markup errors on their own.

Both newer versions build on 2.0, so a site that meets 2.1 or 2.2 Level AA also covers the 2.0 requirements.

Is WCAG 2.0 Still Enough for Compliance?

It depends on which law applies. For Section 508, WCAG 2.0 AA is the named standard, so it is sufficient. For ADA Title II, it is not: the DOJ’s 2024 rule requires WCAG 2.1 AA for state and local governments. Title III has no codified standard, but WCAG 2.1 AA is the benchmark most often cited in demand letters and settlements.

The practical takeaway is to build to WCAG 2.1 or 2.2 AA. It satisfies WCAG 2.0 compliance wherever the older standard is named, and it meets the stricter requirements that are becoming the norm.

Common WCAG 2.0 Failures on Websites

Most WCAG 2.0 failures come from a short list of recurring problems. They appear on sites of every size, and each one maps to a specific success criterion:

• Missing or unhelpful alt text (1.1.1): images with no text alternative, or with generic descriptions such as “image,” leave screen reader users without the information the image carries.
• Low color contrast (1.4.3): light gray text on a white background and brand colors that fall below the 4.5:1 ratio are among the most frequent failures.
• Keyboard traps and mouse-only features (2.1.1 and 2.1.2): menus, modals, and widgets that cannot be operated or exited with a keyboard block users who do not use a mouse.
• Unlabeled form fields (3.3.2 and 4.1.2): fields without programmatically associated labels are hard for screen reader users to complete accurately.
• Video without captions (1.2.2): prerecorded video with spoken content excludes deaf and hard of hearing users when captions are missing.

Many of these issues look minor to a sighted mouse user, which is why they often go unnoticed until someone tests with assistive technology.

How to Test for WCAG 2.0 Compliance

Testing for WCAG 2.0 compliance takes both automated and manual methods. Automated scanners are useful for catching issues such as missing alt attributes and some contrast failures, but they can only check a portion of the criteria. They cannot judge whether alt text is meaningful, whether the reading order makes sense, or whether a keyboard user can complete a task.

A reliable process includes these steps:

1. Run an automated scan to flag obvious, machine-detectable issues.
2. Test with the keyboard only by tabbing through every page, form, and menu to confirm that everything is reachable and that focus is always visible.
3. Test with a screen reader to confirm that content is announced in a logical order and that controls are labeled.
4. Document the results by criterion, prioritizing Level A failures first, then Level AA.
5. Retest after remediation to confirm that fixes work and have not introduced new issues.

FAQ

What is WCAG 2.0?

WCAG 2.0 is the second version of the Web Content Accessibility Guidelines, published by the W3C in December 2008. It contains 61 success criteria organized under four principles: perceivable, operable, understandable, and robust.

Is WCAG 2.0 still valid?

Yes, though newer versions have superseded it. W3C encourages use of the latest version, but WCAG 2.0 remains in force where laws name it, most notably Section 508.

What is the difference between WCAG 2.0 and 2.1?

WCAG 2.1 keeps all WCAG 2.0 criteria and adds 17 more, focused on mobile accessibility, low vision, and cognitive and learning disabilities.

Does ADA require WCAG 2.0?

The ADA itself names no technical standard. The DOJ’s 2024 Title II rule requires WCAG 2.1 AA for state and local governments, and Title III has no codified standard, though WCAG 2.1 AA is the benchmark most often used in settlements. Some older agreements still name WCAG 2.0 AA.

Is WCAG 2.0 AA enough for Section 508?

For web content, yes. Section 508 incorporates WCAG 2.0 Levels A and AA by reference. Many agencies build to WCAG 2.1 AA anyway, since it is the more current standard.