If you are developing a digital library that caters to not only the various needs of your target audience but also to their differing abilities and use of adaptive technologies, then here is an online tool for you. The ATRC Web Accessibility Checker is an experimental service provided by the Adaptive Technology Resource Center (ATRC) at the University Of Toronto. It is also a model system that demonstrates how web pages can be checked for accessibility problems. The accessibility checks in this system are based upon the proposed Open Accessibility Checks (OAC), a universal series of tests that may be applied to HTML pages to determine their compliance with accessibility standards. This accessibility checker also supports W3C's Evaluation And Repair Language (EARL) standard.