This presentation highlights some of the results and implications of a 2019 study on fidelity of implementation of the language of instruction policy in the Philippines. In 2009 the Philippines Department of Education issued Order No. 74 calling for the use of the learners’ mother tongue (MT) as the main medium of teaching and learning (MoTL) in kindergarten through grade 3. The policy introduces Filipino and English as additional languages of instruction, gradually increasing their usage until they take over as the primary MoTL in grade 4. Successfully navigating students through three languages in the early grades is a daunting task. Building on previous studies of MTB-MLE policy implementation in the Philippines, this study examined how teacher assignment, class sectioning (grouping learners by MT), materials provisioning and usage, and teachers’ language usage in the classroom conforms to or diverges from the policy, especially across locations with different contextual factors. It also looked at the factors associated with higher implementation.