Mother-tongue education has increasingly become a keyword in formulations of development goals, especially the Sustainable Development Goals (2015). Achievement of these goals acquires a grave sense of urgency in light of the ever-increasing threat to the very fabric of our linguistic diversity. The basic premise of this article is that Gandhian thought can serve as a guiding principle in our struggle to stem the tsunami of language endangerment. Engagement with Gandhian thought enables us to critically examine the current presuppositions about development and the role of language in nation-building (especially in schools) and also inspires us to look for more sustainable alternatives. This article aims at examining the linguistic world order that Gandhi envisaged--an order where languages do not encroach upon each other. In postulating such a world order, Gandhi shows a keen awareness of the dangers that languages such as English could pose to mother tongues. Furthermore, diversity is not seen as a 'management' problem but rather a necessary condition for all that is human. Emphasis on ensuring that the child in school is an active producer rather than a passive consumer of knowledge, as well as envisaging the school as a resource centre for the neighbourhood ensures that the mother tongues (L-languages) and languages taught in schools (H-languages) enter into a harmonious and symmetrical pedagogical relationship rather than a relationship of violent conflict, which characterises the current linguistic world-order. The article argues that such a pedagogical relationship serves as a necessary component of any sustainable developmental paradigm.