<![CDATA[Despite extensive research on school leadership and teacher performance, limited empirical evidence has compared the relative influence of principals' leadership style, managerial competence, and supervisory competence within geographically challenging educational settings. This study addresses this gap by examining the individual and combined effects of these three competencies on teacher performance in elementary schools in Mandah District, Indragiri Hilir Regency, Indonesia. Employing a quantitative explanatory design, data were collected from 190 teachers selected from a population of 363 using proportional sampling based on the Slovin formula. A validated and reliable questionnaire was utilized, and data were analyzed using multiple linear regression, t-tests, and F-tests. The findings revealed that principals' supervisory competence was the only variable exerting a positive and statistically significant effect on teacher performance (β = 0.255, p = 0.002). Conversely, leadership style (p = 0.247) and managerial competence (p = 0.257) did not demonstrate significant individual effects. However, the simultaneous test indicated that leadership style, managerial competence, and supervisory competence collectively exerted a significant influence on teacher performance (F = 5.532, p = 0.001). The results identify supervisory competence as the most dominant predictor of teacher performance, underscoring the critical role of continuous supervision, professional guidance, and instructional support in enhancing teachers' effectiveness. These findings suggest that educational improvement initiatives should prioritize strengthening principals' supervisory competence while maintaining the balanced development of leadership and managerial capabilities.]]>
