Proficiency in one’s mother tongue is crucial for acquiring a second language. The implementation of Mother Tongue-Based Multilingual Education (MTB-MLE) in the Philippines has sparked debate regarding its effectiveness for Kindergarten to Grade 3. This study compared the reading proficiency levels in Iloko and English among Grade 4 pupils at Tapel Elementary School, Gonzaga East District, Cagayan and identified strategies to sustain and improve reading skills in both languages. Using a descriptive research design, data were gathered from 33 pupils using the Individual Graded Passage Screening Test (IGPST) from the revised Philippine Informal Reading Inventory (Phil-IRI). The study assessed oral reading and comprehension scores and employed a t-test to compare the languages. Results showed most pupils were at Instructional and Independent levels in Iloko, but at the Frustration level in English. This indicates a strong foundation in Iloko, with a need for improved English proficiency. The study recommends strict implementation of Phil-IRI and targeted interventions to enhance English reading skills. These findings support the importance of fluency in the mother tongue for learning a second language and emphasize the need for continuous enhancement of MTB-MLE programs to boost overall reading proficiency and academic achievement.