To what extent can school principals provide effective educational leadership? Research shows that, contrary to textbook images, principals react to their circumstances instead of controlling them and that they spend most of their time on administrative, not instructional, matters. Further entrenching principals in their administrative role is the fact that the principalship is legitimized more by its position in a bureaucratic hierarchy than by any instructional expertise on the part of the principal. However, principals could base their legitimacy on instructional expertise. To do so they must take a more active role in instruction; recent research, for instance, shows that effective schools' principals are more active in instructional supervision, evaluation, and leadership. A redefinition of the principal's role will mean that principals must acquire new skills and practice closer overseeing and improvement of instruction. This instructional supervision must be based on three points: the classroom should be the focus of activity, teachers' and pupils' concerns must take priority, and principals should give teachers objective feedback on their classroom work. (Author/RW)