This document discusses mother tongue-based multilingual education (MT-Based MLE) in South Asia. It defines MT-Based MLE as using students' mother tongue and additional languages as languages of instruction in school. The rationale provided is that using children's mother tongue builds confidence and a strong educational foundation, while additional languages help build a bridge to other languages. Successful MT-Based MLE programs introduce additional languages orally before introducing literacy and use both the mother tongue and additional languages throughout primary school. Strong education policies that support linguistic diversity and MT-Based MLE are needed to ensure quality education for all students.