This paper explores student and school level factors associated with 15-year-old students' reading performance in five Southeast Asian (SEA) countries. It investigates predictors of reading performance, including student gender, economic, social, and cultural status (ESCS), social well-being, and experiences of bullying at the student level. It also explores the school sector, school climate and the proportion of socioeconomically disadvantaged students at the school. Using Hierarchical Linear Modelling (HLM), this study identifies significant relationships between these student-level factors and learning outcomes, illustrating the complex associations that shape academic success. The findings align with prior research, highlighting disparities in reading skills between genders and the negative association of bullying with academic performance. Additionally, the study emphasizes the positive association of ESCS and social well-being on reading achievements, underlining the importance of socioeconomic status and socio-emotional wellbeing in students' learning success. The associations with school level factors vary across Southeast Asia.