Besides Hallingers and Heck’s broad review, several studies conducted in the 1990s and 2000s have also explored the effect of instructional leadership on teacher and student outcome. With respect to the effect of principals on teachers, Shepperd(1996)[1] study in Canadian schools revealed that principals’ instructional leadership activities are positively related to the level of teacher commitment to the school, professional involvement, and innovativeness in the school.