"When it was released in 2011, Drupal 7 was the most accessible open source content management system (CMS) available. I expect that this will be true until the release of Drupal 8. Web accessibility requires constant vigilance and will be something that will always need attention in any piece of software striving to meet the Web Content Accessibility Guidelines (WCAG) 2.0 guidelines.
This has been useful for many organizations that, for legal, economic, or ethical reasons, want to make their sites as accessible as they can be.
What makes Drupal different from most other CMSs is that the focus has been on improving Drupal Core’s accessibility on all levels (public, content editor, administrator, and developer). Fixing problems in Core allows us to fix accessibility problems at the source, and they propagate by default to themes and modules that are used." Mike Gifford, OpenConcept Founder and President