<![CDATA[The challenges of the 21st century require teachers to develop professional competence in implementing the teaching and learning process, which is achieved through Continuous Professional Development (PKB). The low level of PKB at Al Asriyyah Nurul Iman Junior High School demonstrates that government efforts to improve teacher professionalism have not been successful. This study aimed to determine the influence of principal leadership and school culture, through work ethic, on the professionalism of junior high school teachers in Bogor Regency. This study employed path analysis through two regression analyses: 1) a regression analysis between principal leadership, school culture, and work ethic on teacher professionalism, and 2) a regression analysis between principal leadership and school culture on work ethic. The functioning of the intervening variables was tested using the online Sobel Test Calculator. The results of the regression analysis obtained standardized coefficients for the principal leadership variable of 0.068, for school culture of 0.502, and for work ethic of 0.254. The results of the regression analysis obtained standardized coefficients for the principal leadership variable of 0.342 and for school culture of 0.38. The Sobel test results yielded a Sobel test statistic of 2.12 with a significance level of 0.017. The Sobel test results yielded a Sobel test statistic of 2.216 with a significance level of 0.01. These results indicate that principal leadership is not the primary factor influencing teacher professionalism, but rather work ethic as an intervening variable. Keywords: Principal Leadership, School Culture, Work Ethic, Teacher Professionalism.]]>
