The author looks through Albert Bandura's self-efficacy lens onto the effects it likely has on school principals' effectiveness. Self-efficacy should be viewed as a principal's belief in his or her capabilities to structure a particular course of action in order to produce desired outcomes. Principal self-efficacy has been linked with effective leadership, effective schools, the school restructuring process, and the quality of teaching and learning. Principals' thoughts and actions influence the school culture, and research indicates that a principal can have a negative effect during a period of change. For these reasons, it is important for principals to have a strong sense of self-efficacy.