Abstarct: The purpose of this study was to the effect of leadership styles on citizenship behavior with the mediating role of job engagement and motivating language in sport organizations. The present study was descxriptive-correlational and time-cross-sectional. The statistical population of the research was all employees of sports and youth departments in Golestan (212 people) and Semnan (117 people) provinces, and 233 people were selected as a sample using stratified random sampling. The research tools were five standard questionnaires on servant leadership style by Leyden et al. (2015), transformational leadership style and citizenship behavior by Buil et al. (2019), motivational language by Mayfield et al. (1995), work engagement by Schaufeli et al (2006). Ten experts and sport management professors assessed and confirmed the validity of these questionnaires. To determine the reliability of the questionnaires, a preliminary study was conducted among the employees of the Golestan and Semnan sports departments, and the results of Cronbach's alpha showed that the questionnaires had acceptable reliability. Structural equations were used to investigate the research hypotheses. In this study, SPSS software version 25 and SmartPLS3 were used. Analyzing the research model showed that the transformational leadership style positively and significantly affects motivating language. However, servant leadership did not show a significant effect on motivating language. Transformational leadership, servant and motivating language significantly affect work engagement. Work engagement and servant leadership also positively and significantly impact citizenship behavior. However, the effect of transformational leadership on citizenship behavior was not confirmed. Motivating language mediates the relationship between transformational leadership and work engagement. The mediating role of motivating language in the relationship between servant leadership and work engagement was not confirmed. Work engagement is mediating the relationship between servant leadership and citizenship behavior. However, the same variable was not established as a mediator in the relationship between transformational leadership and citizenship behavior. Thus, considering the positive impact of leadership styles on motivating language, work engagement and citizenship behavior, managers should choose the appropriate leadership method according to different leadership styles. Also, motivating language creates and develops work engagement in employees and extra-role behaviours in the organization.