Lesson 1 of 6

WCAG Levels, Principles, and Section 508

Hook

Before you check a single color contrast ratio, you need to know which rules actually apply to your project — because "WCAG-compliant" can mean three very different workloads depending on the level, and US government work often points to a separate standard entirely.

Core idea

WCAG 2.2 success criteria are grouped into three conformance levels: A, AA, and AAA. Each level builds on the one before it — you can't claim AA without also meeting every A criterion.

  • Level A covers the baseline: content that would be unusable for some people without it. Examples: images need text alternatives, and nothing may rely on color alone to convey meaning.
  • Level AA adds criteria that remove serious, common barriers without being hard to implement broadly. Examples: text contrast of at least 4.5:1, and visible keyboard focus indicators.
  • Level AAA adds the strictest criteria, often with real tradeoffs (like a 7:1 contrast ratio) that aren't realistic for every product or brand.

Most organizations target AA. It's the level most laws and procurement contracts actually require, and it balances real accessibility gains against design and engineering cost.

In the US, Section 508 is a separate law that applies to federal agencies and anyone building for them. Section 508 doesn't invent its own rules anymore — it points directly at WCAG 2.0 Level AA as the legal floor. So Section 508 and WCAG aren't competitors; Section 508 is the legal requirement, and WCAG AA is the technical standard it adopts. If your client is a private company, WCAG itself (often referenced by the ADA or a contract clause) governs instead.

Worked example

Say you're designing a benefits portal for a US federal agency. Your PM asks, "Do we follow WCAG or Section 508?" The answer: both, because they point to the same target. You'd tell the team: "We need to meet WCAG 2.0 AA at minimum, because that's what Section 508 requires for federal systems. If we want to use WCAG 2.2, we should meet its AA criteria too, since the newer version only adds criteria — it doesn't remove the Section 508 baseline." That framing stops the team from treating the two standards as separate checklists to reconcile.

Takeaway

Know your level before you start: A is the floor, AA is the realistic target for almost every product, and AAA is rarely a full-site goal. If you're building for the US federal government, Section 508 is the law, and it's satisfied by meeting WCAG AA.