This study examines the impact of curriculum-based measurements (CBMs) on literacy assessment in Omani schools, with a focus on how these tools affect Emergent and Proficient Readers. Grounded in the concepts of graphocentrism and ableism, the research highlights the systemic biases embedded within standard literacy practices that favour written language and normative learning trajectories. Through the analysis of literacy outcomes among Grade 1 students aged between six and seven years, the study reveals significant performance disparities, indicating that current assessment practices disproportionately benefit Proficient Readers while marginalising those with diverse learning needs. The findings underscore the need for a decolonising approach to literacy that incorporates multi-literacies and culturally relevant pedagogies, advocating for educational reforms that recognise and value the diverse linguistic and cultural backgrounds of students. By shifting toward more inclusive assessment methods, Oman can better address educational inequities and foster an environment where all students have the opportunity to succeed. This research contributes to the global discourse on educational equity, suggesting that literacy assessments be restructured to ensure inclusivity and fairness in the evaluation of student competencies.