This chapter presents an investigation into the accessibility of official tourism websites of 26 EU member states. It is divided into two main parts. The first part is focused on the theoretical background of web accessibility, where the definition of accessibility, accessibility laws, accessibility recommendations, accessibility automatic tools, and related research are presented. The second part includes an empirical investigation with the main focus being on evaluating the compliance of tourism websites with web content accessibility guidelines 2.1 (WCAG 2.1) and the identification of the most commonly violated WCAG 2.1 success criteria. The results, which are based on automatic tool multiguideline accessibility usability validation environment (MAUVE), show that all investigated websites included at least one error. The most frequently identified errors were related to success criteria (1) reflow; (2) name, role, value; (3) link purpose (in context); and (4) purpose identification. Based on the acquired knowledge, the recommendations for improving web accessibility are presented.