Research studies cited show that principals do have some authority over how they use their time, resources, and power. The intent of this paper is to point out that it is important for principals to work with teachers for the purpose of improving teaching, that the principal has a choice as to what interventions to make in striving toward this goal, and that the effects on teachers are related to the interventions selected. In order to demonstrate these points, several examples are used from the Principal-Teacher Interaction Study being conducted by the Concerns-Based Adoption Model project at the Austin campus of the University of Texas. The examples relate both to what principals do as change facilitators and to the effects of principals' interventions on teachers during the change process. The examples are followed by a discussion of the effects of these interventions on the teachers involved. The paper concludes that the interventions made by the principals did have effects on teachers and teachers' use of an instructional innovation. (Author/MLF)