Instructional leadership and student achievement in a centrally regulated system: A school-level test of academic optimism as an organisational pathway

This study examines how instructional leadership is associated with school-level student achievement within a centrally regulated education system, positioning academic optimism as a key organisational mediator. Rooted in the indirect-effects perspective, the study investigates whether leadership relates to student outcomes by shaping a collective belief system defined by academic emphasis, collective efficacy, and trust. Data were collected from 934 teachers across 205 Anatolian high schools in Türkiye and merged with official achievement records for 41,847 tenth-grade students. School-level structural equation modelling, controlling for family socioeconomic status, reveals a theoretically anticipated competitive mediation pattern. Instructional leadership shows a statistically significant positive indirect association with achievement through academic optimism, while its residual direct association with achievement is negative. These results suggest a dual process in centralised high-stakes accountability contexts: principals indirectly promote achievement by cultivating an optimistic academic culture, whereas the negative direct path reflects supervisory escalation in response to performance pressure. The findings demonstrate that leadership's association with achievement is primarily realised through the school's collective belief system, underscoring the importance of examining specific organisational mechanisms rather than total or direct effects alone. All findings are interpreted as associational rather than causal.