This study examined the intentions of education policy documents and the conceptualizations of secondary school principals and teachers regarding curriculum differentiation. Regular and special day schools were selected using purposive sampling based on their experiences with different types of curriculum differentiation. Two school principals and 17 subject teachers were selected using purposive and convenience samplings, respectively. The study analyzed national education policy documents (e.g., education and training policy and curriculum framework) and collected interview data from school principals and teachers. The two main national education policy documents conceptualize curriculum differentiation in terms of various tracks, like fields of study, streams, and school types. The other national document, the guideline for curriculum differentiation, emphasizes the differentiation of curriculum components--contents, instructional processes, assessment strategies, and learning environments--and highlights the importance of inclusive classrooms. Principals' and teachers' conceptualizations of curriculum differentiation vary across three levels: lacking awareness, holding divergent views, and aligning with policy intentions. The absence of a coherent policy guide and the lack of engagement of principals and teachers in reform ideas have contributed to these diverse conceptualizations. Additionally, the policy intentions seem inadequately addressed through curriculum differentiation practice by school types, such as regular, special day, and boarding schools, which do not correspond to variations in the types and levels of difficulty of the school subjects taught.