This paper presents a programme designed to deepen knowledge regarding diversity and to sustain equality and equity in participation during class activities in high sociolinguistic diversity classrooms. We investigated a four-stage programme integrating all students' heritage languages in cooperative school activities in one 4th grade class in the French-speaking canton of Geneva in Switzerland. Activities that the teacher engaged in included: (a) activities devoted to openness to others, (b) activities devoted to linguistic diversity, (c) activities devoted to cultural diversity, (d) cooperative activities, relying on heritage languages and personal family stories. The three first stages aimed to help students feel accepted and comfortable when participating in multilingual cooperative activities. Feedback from the teacher, students and parents indicated that this programme found its place in the regular curriculum and participants appreciated it. This programme also improved students' sense of belonging to the class and a feeling of relatedness.