The first of two studies provided validity data on the Teacher Irrational Belief Scale that measures a set of beliefs of teachers previous research has found to be associated with teacher stress. Employing a sample of 850 primary and secondary teachers in Australia, an exploratory factor analysis resulted in four distinct factors: Self-downing, Authoritarianism, Demands for Justice, and Low Frustration Tolerance. These four sub-scales demonstrated adequate internal reliability and correlated with self-ratings of stress occasioned by different teaching stressors. In a second study, 140 teachers and 26 teachers retired from teaching because of stress completed the Teacher Irrational Belief Scale and a measure of teacher stress. Teachers retired from teaching due to stress scored higher on sub-scales of Self-downing and Low Frustration Tolerance than teachers still teaching. These results are discussed in terms of Ellis' theory of REBT and implications for consultants and teacher educators offering stress management programs and support for teachers.