Abstract
This paper examines the relationship between school segregation, academic selection, and educational performance in post-conflict Northern Ireland. While integrated education has been promoted as a mechanism for reconciliation since the Belfast/Good Friday Agreement, limited attention has been paid to how institutional structures shape system-wide inequality and attainment. Using aggregated school-level data for 2018–2019 and 2022–2023, the study applies a segregation index to measure religious separation across all major school types and analyses GCSE performance while controlling for socio-economic disadvantage and special educational needs. The findings show that Northern Ireland’s education system remains highly segregated by religion, with little evidence that segregation self-corrects between primary and post-primary schooling. Integrated schools are consistently the least segregated but face performance challenges within a selective, two-tier system. After controlling for disadvantage, Catholic Maintained secondary schools outperform both Integrated and Controlled secondary schools, while no significant differences emerge between Catholic and Protestant grammar schools. The analysis demonstrates that segregation and academic selection operate jointly to reproduce inequality, constraining the growth of integrated education despite strong legislative and normative support. The paper contributes a system-level perspective to debates on education, inequality, and peacebuilding in divided societies.