Empirical research advocates that school leadership plays a significant role in shaping worker commitment, and how important the latter is regarding scholastic outcomes. This study examined the phenomenon in the Kuwaiti public school by attempting to identify the mediating effect a teacher's Trust In their school's Principal (TIP) has upon the relationship between Organizational Justice (OJ) and Teacher Commitment (TC). More specifically, this study attempted to: (1) describe and compare TC in Kuwaiti public schools against the demographic variables of gender, nationality, years of experience and school level; (2) examine the total effect of OJ on TC; and (3) determine whether TIP has significant mediative effects upon the relationship between OJ and TC. The research sample comprised 200 teachers from 30 different Kuwaiti public schools. Study participants revealed that TC, OJ and TIP are all at mediocre levels in Kuwaiti schools. The study also indicated that elementary school teachers have significantly lower TC than their colleagues working in high schools. Moreover, the study demonstrated that TC is positively and significantly related to OJ and TIP. The study also showed that TIP does indeed act as a mediator between OJ and TC. The researcher provides relevant recommendations based on these findings.