This study examined the effects of supervisory practices of school principals on the work performance of teachers. A survey was conducted with a sample of 80 teachers from secondary schools in the District of New Bataan. The results showed were all evaluated high with descriptive equivalent of often manifested. Further, the result of the level of work performance of teachers as measured by teachers competencies in term of mastery/knowledge of the subject matter, management of learning, guidance skills, utilization of teaching materials and assessment practices. The result also revealed that there was no significant relationship between the supervisory practices of school principal and work performance of teachers. From the results of study, it was recommended that the, school principal must take time to orient teachers on the aspects of leadership, as well as the importance of holding seminars on how to maintain very high level of harmony and professionalism, school principals and teachers should always strive to improve educationally or upgrade to keep abreast of new trends of leadership, establish open lines of communication between school principals and teachers and further research is encouraged to examine closely the relationship between teacher and school principals in terms of work performance.