Web Accessibility aims to provide usable web information and services to as many people as possible. Despite the availability of standards and the presence of legal obligations, Web Accessibility often remains unsatisfactory. Through a multi-step approach, the present study addresses the question of how web practitioners form their intention to consider Web Accessibility in the development process. Based on a systematic literature review, twelve main salient beliefs influencing the intention to consider Web Accessibility were identified. Applying the Theory of Planned Behavior, a theoretical model integrating these main salient beliefs was compiled and a questionnaire to test the model developed. A total of 342 web practitioners in various professional roles answered the questionnaire in an online study. Path analysis revealed that intention to consider Web Accessibility is stronger when users actively promote their needs, when web practitioners see Web Accessibility as part of their professional role, and when the consideration of Web Accessibility is perceived as beneficial for the quality of a product. Hence, it is recommended to involve users with a variety of abilities in the development process, to emphasize the responsibility and specialist role of web practitioners, and to actively promote Web Accessibility as a quality feature of a product.