A whole-school approach to foster competences for democratic culture, described by the Council of Europe's Reference Framework of Competences for Democratic Culture, implies the active involvement of all actors in three areas of school life: teaching and learning, school governance and culture, and co-operation with the community. The European Centre for Modern Languages' project Des environnements d'apprentissage optimisés pour et par les langues vivantes (EOL) similarly assumes that a whole-school approach is essential in the promotion of plurilingual and intercultural education in schools. The article illustrates the EOL project: the core principles of its approach, the tools, materials and examples of practices. The project and its followup activities have proved that setting up language learning friendly environments requires decisions at different levels so as to introduce mechanisms and routines. Considering language education as a key factor for social cohesion, the aim of the article is to answer the question of what schools should do so as to go beyond a one-off, isolated project to unite all stakeholders around a shared language plan for school, which fosters competences for democratic citizenship.