This investigation developed and validated a simulation device to measure a teacher's ability to identify verbal and nonverbal emotions expressed by a student. The instrument, Teacher Affective Sensitivity Scale (TASS), consisted of videotaped excerpts of teacher-learner interactions from actual and simulated episodes. Each simulation excerpt was accompanied by two multiple-choice items. The subjects, preservice and in-service teachers and counseling practicum students, selected the answer from each multiple-choice that they believed most accurately described the affective state of the pupil viewed on the screen. Assessments of scale reliability; scale construct; and predictive, concurrent, and content validity were made. Based on the results of the tests of reliability, it was concluded that the current form of the TASS can be used as a research tool but not as an instrument for individual appraisal. Because the subject groups employed to obtain validity assessments did not experience a treatment specifically designed to increase levels of affective sensitivity, it was recommended that further validation studies be made. (MJM)