Teacher efficacy has proved to be powerfully related to many meaningful educational outcomes such as teachers’ persistence, enthusiasm, commitment and instructional behavior, as well as student outcomes such as achievement, motivation, and self-efficacy beliefs. However, persistent measurement problems have plagued those who have sought to study teacher efficacy. We review many of the major measures that have been used to capture the construct, noting problems that have arisen with each. We then propose a promising new measure of teacher efficacy along with validity and reliability data from three separate studies. Finally, new directions for research made possible by this instrument are explored. (author abstract)