In Nigeria, secondary school systems are diverse and often underperform in terms of student enrollment and educational outcomes. Multilevel regression analysis was employed to assess the adoption rates of secondary school systems in Nigeria. The model accounts for both individual-level and school-level data. Secondary school system adoption rates varied significantly across regions, indicating that contextual factors play a critical role in their implementation. The multilevel regression analysis provided insights into the determinants of secondary school systems' adoption in Nigeria. Future research should consider longitudinal data to better understand how these systems evolve over time. Secondary schools, Multilevel Regression Analysis, Adoption Rates, Nigerian Education The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.