A total of 60 students in teacher training enrolled in a Principles of Teaching Methods course participated in this study. The course consisted of four-hour weekly sessions, in which the students attended two-hour lecture sessions and taught eight to ten micro-lessons. In the microteaching laboratory, the student-teachers were arranged into groups of six to eight students. All lessons were videotaped; and immediately following the lesson, the student, supervisor and peers viewed the tape. The tapes were critically discussed, and alternative courses of action were outlined for the next lesson. The computer analysis of the data provided a diagnostic card for each student and served as a basis for laboratory supervision. Results are given. Since all the students achieved similar levels of performance towards the end of the treatment, it is concluded that the treatment is effective for student-teachers with low-entry behavior as well as for those who begin the training program with some teaching experience. (CK)