This study examines how transformational leaders influence research and development (R D) workers commitment to their organizations and leaders. The study investigates the mediating role of organizational justice (i.e., procedural and interactional) based on social exchange theory and the moderating role of span of control in this relationship. In a sample of 445 Turkish R D personnel, the study finds that transformational leadership significantly influences followers organizational commitment partially through procedural justice and their supervisory commitment partially through interactional justice. Second, the findings reveal that transformational leaders boost perceptions of procedural justice and organizational commitment when the span of control is relatively narrow. Interestingly, when the span of control is large, transformational leadership has significant positive effects on supervisory commitment, but no significant effects on organizational commitment among R D workers.