An Investigation into The Impact of Leadership Styles on Teacher Performance in The Context of Public High Schools in Burundi

School leadership style is widely regarded as a decisive influence on teacher performance, yet empirical evidence from Burundian public schools has been almost entirely absent from the literature. This study examined how leadership styles adopted by public high school principals affect teacher performance in Burundi and proposed recommendations for school leadership improvement. Three research aims guided the study: (1) to assess teachers' and principals' perceptions of leadership styles and teacher achievement; (2) to analyze the relationship between principals' leadership styles and teacher performance; and (3) to recommend leadership styles that would improve public school performance. A descriptive survey design was employed with principals and teachers as the target population across 20 randomly selected public high schools in the Educational District of Bujumbura City (EDBC), Burundi. Using Nassiuma's formula, a sample of 150 respondents was drawn from an accessible population of 452. Quantitative data were collected using structured Likert-scale questionnaires and analyzed in SPSS v.22 using descriptive statistics (frequencies, means, percentages, standard deviations) and Pearson correlation; qualitative data were collected through semi-structured interviews with school principals and analyzed thematically. A pilot study pre-tested the validity and reliability of the research instruments. Results showed that the democratic leadership style was the least practiced, with the lowest mean of 1.525, while laissez-faire (M = 2.5608) and, most prominently, autocratic leadership (M = 2.725) were the most commonly practiced styles. Leadership style overall was significantly associated with teacher performance (r = 0.739**), with democratic leadership showing a very strong positive correlation with performance (r = 0.957**), laissez-faire a moderate correlation (r = 0.523**), and autocratic leadership only a weak correlation (r = 0.378**). Thematic analysis of principal interviews identified autocratic leadership, democratic leadership, laissez-faire leadership, and training as the dominant themes, with strictness, threat, inclusivity, autonomy, and the absence of formal leadership training recurring across principals' accounts. The study concludes that autocratic leadership practices should be discouraged as they contribute to poor teacher performance, and recommends mandatory leadership training for all school principals together with the promotion of democratic leadership as the style most conducive to a productive school environment, while cautioning that leadership style alone is insufficient without adequate principal training. Further comparative research across Eastern African countries is recommended to establish the wider regional generalizability of these findings.