Accessibility can be identified as the offering of equal rights, equal opportunities and full participation for all citizens in society. As a social issue, accessibility is situated within an important legal and normative framework that covers all dimensions of human activities, including employment, working conditions, access to the built environment, transport, use of resources, online education and training. However, whilst directives, regulations and technical standards specify the desirable characteristics of environments, such as built environment, transport, public spaces and new technologies, they do so in a disjointed way. Thus, accessibility can bring a universal approach to the inclusion of all in society; however, in reality, it is implemented in a piecemeal fashion. Because it extends across different areas and is included in the diverse and evolutionary dynamics of people, accessibility can be tackled within the approach developed by francophone ergonomics. Such a systemic approach focuses on the intrinsic and aims to contribute to a design environment that is accessible to everyone. We begin with a definition of accessibility and identify the reasons why this issue is of interest to ergonomics. We then present the legislative policy changes that have occurred in the fields of disability and accessibility in recent decades. Finally, we discuss the problem of accessibility in terms of designing appropriate situations for everyone through the bringing together of accessibility-for-use and accessibility-in-use criteria. Our proposal is grounded on the historical contributions from the fields of ergonomics and psychology on which it draws.