The aim of this research was to investigate the effect of principlas' transformational leader behaviors on teachers' organizational commitment. In the research, causal-comparative and relarional survey methods were used. The study group, defined according to convenient sampling method, was composed of 260 public school teachers working in five provinces in the Central Anatolia Region in Turkey. The data was gathered with "Transformational Leadership Scale" and "Teachers' Organizational Commitment Scale", in the spring semester of the 2021-2022 academic year. Descriptive statistical analysis, independent groups t-test, test of variance (ANOVA), Pearsons' corelational analysis and regresion analysis were employed in the analysis phase. The findings showed that both principals' transformational leadership levels and teachers' organizational commitment levels were moderate. It was observed that teachers' perceptions about their principals' transformational leadership behaviours and organizational commitment levels didn't show a significant difference among the groups of gender, age and work experience. It was found that there was a significant relationship between principals' transformational leadership behaviours and teachers' organizational commitment, and the former was a significant predictor of the latter. It was concluded that principals' transformational leadership behaviors might be effective in enhancing teachers' organizational commitment. In this frame practical, theoretical and research recommendations were developed.