Effective principals use a variety of techniques to develop productive climates and to motivate students' learning. One of such techniques for effective classroom management is supervision of instruction. This study was therefore conducted to ascertain principals' performance in supervision of classroom instruction in Ebonyi State secondary schools. A sample of 360 teachers completed a 12-item questionnaire designed for the study. Data were analysed using mean, standard deviation and t-test statistics. The results of the study showed that the principals' performance in supervision of classroom instruction in secondary schools in Ebonyi State was effective. It was also found that there was a significant difference in the performance of principals in most of the instructional leadership functions in secondary schools in Ebonyi State based on location of schools, but there was no significant difference in the performance principals in most of the instructional leadership functions in secondary school in Ebonyi State based on gender. On the basis of the findings of this study, it was recommended among others; that principals as instructional leaders should give supervision of classroom instruction the place it deserves in their work.