Purpose: The present study aimed to investigate whether the sub-dimensions of transformational leadership are differently influenced by middle-leaders' personality traits from the Big Five typology, namely, extraversion, conscientiousness, openness to experience, agreeableness, and neuroticism, and whether the sub-dimensions of transformational leadership influence teachers' professional and organizational commitment differentially. Design/methodology/approach: Data were collected from two sources: 114 middle-leaders and 282 teachers randomly chosen from elementary schools in Israel. Hierarchical regression analyses and structural equation modelling were used to test the research hypotheses. Findings: First, the findings indicated that the teachers perceived their middle-leaders as transformational leaders without distinguishing between the sub-dimensions. Second, transformational leadership was positively correlated to teachers' professional and organizational commitment. Finally, positive relationships were found between the middle-leaders personality traits of agreeableness and openness to experience and teachers' commitment. The study findings point to two paths to facilitate teachers' professional and organizational commitment, either through the middle-leaders transformational leadership or their personality. Originality/value: Although recent research has shown that leaders' personal traits are critical components in leading a team effectively and promoting employee behaviors, few studies in the educational context have focused on the differential impact of the Big Five typology on middle-leaders' tendency toward the sub-dimensions of transformational leadership (TL) and its implications for teachers' commitment. By integrating research from both educational and non-educational literature, the goal of the present study, then, is to address these important yet relatively unstudied issues.