Abstract This study examines changes in Filipino reading proficiency among elementary and junior high school students in Makati City through pre-post Philippine Informal Reading Inventory (PHIL-IRI) assessment analysis. Employing a mixed-methods longitudinal comparative design, data were collected from multiple schools across Grades 3-10 during School Years 2023-2024 and 2024-2025. The research analyzed reading proficiency distributions across three standardized levels: Frustration (FR), indicating students struggle with basic reading comprehension; Instructional (INS), suggesting students can read with guidance and support; and Independent (IND), demonstrating students can read fluently without assistance. Findings reveal contrasting patterns between educational levels. Elementary schools showed mixed results with concerning shifts from Independent to Instructional levels, particularly Grade 4 experiencing the most significant decline (-24.1% Independent readers). The average decrease in Independent level readers across all elementary grades was 15.6 percentage points, while Instructional level readers increased by 11.7 percentage points. Several schools demonstrated remarkable improvement while others experienced substantial declines, indicating significant institutional variations requiring targeted intervention. Junior high schools exhibited consistent improvement patterns, with a 69% decrease in frustration-level readers and 31% increase in independent readers across all grades. Exceptional performances were observed at San Isidro National High School and Bangkal High School, demonstrating that substantial improvements are achievable with appropriate interventions. School-level variations suggest that institutional factors significantly influence reading instruction effectiveness. These findings provide crucial insights for educational policymakers and practitioners in developing effective reading intervention programs and resource allocation strategies to enhance Filipino literacy outcomes in urban educational settings, highlighting successful practices for replication and identifying schools requiring immediate support.