The educational sector in Nigeria faces significant challenges, particularly in secondary school systems which are crucial for preparing students for tertiary education and employment. A difference-in-differences approach will be employed to assess changes in secondary school systems over time. The DiD model will compare treated and control groups to estimate causal effects. The analysis revealed that certain educational reforms had a significant positive impact on student enrollment, with an estimated increase of 15% in enrollments post-reform. While the DiD model suggested improvements, there is still room for further policy interventions to enhance system reliability and effectiveness. Further research should explore long-term impacts and potential barriers to implementation. Policy recommendations include strengthening teacher training and infrastructure development. secondary schools, Nigeria, Difference-in-Differences (DiD), educational reforms The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.