This research investigates the impact of class size on student performance in Azerbaijani public secondary schools, utilizing State Examination Center (SEC) final exam scores as a key indicator. Data from the Ministry of Science and Education is analyzed, covering approximately 80,000 9th and 11th-grade students in 4,400 schools. The primary objective is to understand the relationship between class size and academic outcomes. Through correlation and regression analyses, this study explores the dynamics linking class size with student performance. The results consistently reveal a positive correlation between class size and student performance, even after controlling for different school categories. These findings hold significant implications for educational policy, providing valuable insights into the complex interplay of factors influencing student outcomes. The study contributes to the ongoing discourse on class size and student achievement, underscoring that while class size is a pivotal factor, it exists within a broader educational context where numerous variables shape academic success.