Background: The W3C Web Accessibility Initiative has issued guidelines for making websites better and easier to access for people with various disabilities (W3C Web Accessibility Initiative guidelines 1999). Method: The usability of two versions of a website (a non-adapted site and a site that was adapted on the basis of easy-to-read guidelines) was tested with two groups of 20 participants. One group had intellectual disabilities but could read, the other group had no identified intellectual disabilities. In a 2 x 2 experimental design, it was investigated whether the easy-to-read website was indeed better accessible and usable for the participants with intellectual disabilities. Results: The adaptation of the website worked well for participants with intellectual disabilities. Users without identified intellectual disabilities were as effective with the adapted site as they were with the non-adapted site. Conclusion: The results form an empirical basis for recommendations about applying guidelines for easy-to-read text on websites for people with intellectual disabilities.