The purpose of the study was to develop the Teachers' Mental Toughness Questionnaire (TMTQ). The questionnaire was developed in six stages: item generation, content validity, exploratory factor analysis, reliability tests, convergent validity tests, and discriminant validity. The factor analysis indicates that it measures six factors: team, liveliness, adaptation, stress, burnout, and facing challenges and assertiveness. Reliability demonstrated acceptable to good levels of internal consistency and stability over time. Convergent validity and discriminant validity were also demonstrated. Hence, the questionnaire was found to be a psychometrically sound six-factor measure of mental toughness among teachers.