The study examined the effect of instructional leadership on school performance. Instructional leadership is a process that how quality practices: building and sustaining the school vision, monitoring of curriculum and instruction, leading a learning community, data gathering and assessing, and shared leadership were implemented by head teachers effectively. School performance is defined as the attainment of targets by teachers, students and schools. In district Sahiwal, head teachers were evaluated for instructional leadership by their SSTs (N=1026) on HTEQ. For school performance, a score of student achievement were obtained from their schools, while data on factors: cleanliness of schools, student presence, the functionality of facilities, and teacher presence were obtained through monthly visit reports of MEAs. The study revealed that head teachers were used practices of instructional leadership effectively and excellent level of schools' performance were found. The study explored a moderate relationship between variables (r=.54), and a 39 % variance in school performance could be explained through instructional leadership. The recommendations were also added in the study.