The hypotheses of this field study, conducted in connection with the Teaching Techniques Laboratory at the University of Illinois, were that student teachers who had participated in a supervised, laboratory, microteaching experience would: 1) receive more favorable pupil evaluations of an initial and final teaching effort on the Teacher Performance Appraisal Scale; 2) receive more favorable pupil evaluations of their overall effectiveness on the Illinois Evaluation Questionnaire; 3) be judged by their cooperating teachers to be ready earlier to assume full responsibility for classroom instruction; and, 4) have higher Indirect/Direct ratios as revealed by Flanders' interaction analysis technique. The population consisted of two different sections of a required methods course, each comprising 25 social studies student teachers, one group having participated in the training, the other not. Thirty-three tapes were obtained of initial teaching efforts; thirty-two of these were re-taped during the last week of student teaching. The first two hypotheses were confirmed; the latter two were not. The lack of significant results on the fourth hypothesis, however, was felt to be at least partially attributable to an uncontrolled variable. The data strongly suggest that videotaped microteaching can be an effective innovation in teacher preparation. (JLB)