The purposes of this study were (I) to determine the relationship of teacher temperament to effectiveness in the classroom and (2) to determine the relationship of the teacher's temperament to the teacher's sex, to the grade level taught, to the area taught (special education or regular education), and to the subject taught. It was hypothesized that (I) there is no significant relationship between the teacher's temperament and his effectiveness in the classroom, (2) there is no significant relationship between the teacher's temperament and sex, (3) there is no significant relationship between the teacher's temperament and the grade level he teaches (elementary or secondary), (4) there is no significant relationship in the teacher's temperament and the area he teaches (special education or regular education), and (5) there is no significant relationship between the teacher's temperament and the subject he teaches.