Language policies in multilingual contexts like Madagascar can significantly influence education outcomes. A survey research approach was employed to collect data from a representative sample of primary school students and teachers across different regions of Madagascar. The analysis revealed that the consistent use of Malagasy as the medium of instruction significantly improved student performance in language-based subjects compared to English-only teaching environments. The findings suggest that policy interventions aimed at consolidating Malagasy as a key educational language can lead to better academic outcomes for students in multilingual settings. Educational policymakers should prioritise the adoption of Malagasy as the primary language of instruction and support its development within school curricula. Language Policy, Education Outcomes, Multilingual Madagascar, Survey Research