The principal’s role is to promote academic performance. The success or failure of a school is usually attributed to the principal. He or she is the pivot around which many aspects of the school revolve, being the person in charge of every detail of running the school, be it academic or administrative. Schools can make a difference to students’ achievement and the principal’s leadership is one factor determining that success. It is therefore important that the performance of a school is appraised against the performance of the person who leads it. The researcher was prompted to carry out this study because of the persistent poor performance in Kenya Certificate of Secondary Education examinations in many secondary schools in Tigania West Sub-county. The objectives of the study were to: find out the instructional leadership activities the principal engages in to improve students’ academic performance, determine the approaches the principal uses to supervise instruction in order to improve students’ performance, find out the extent to which principals involve teachers in decision making in order to improve students’ performance, and find out the challenges principals encounter in improving students’ performance. The study was guided by the systems theory of organizations which postulates that schools are like open systems and emphasizes the consideration of the relationships between the school and its environment as well as what goes on within the school. The study used descriptive survey research design. The study sample composed of 10 schools out of 26 Public secondary schools in the Sub-county. Each school yielded 24 students and 5 teachers selected through systematic sampling plus the principal purposively selected giving a total of 300 respondents. The researcher collected data using questionnaires. Data was analysed using descriptive and inferential statistics. The results were presented in summary form using frequency distribution tables, bar charts and pie charts.