The issue of leadership competencies has been the subject of scientific research since 1980s. Through this study, it is determined whether instructional competencies of school principals vary depending on the type of school they work at and their field. Data obtained as a result of this study were associated with the effect of the field and type of school in selecting school principals on the instructional competencies of school principals. It is thought that the findings of the study will provide significant data in selecting and educating school principals, which is among the underlying factors of the effective school concept. (Contains 2 tables.)