ABSTRACT: To determine its effects on foreign language teaching, preservice and inservice foreign language teachers were taught interaction analysis, a category system for describing pupil-teacher interaction. The preservice teachers received this training while student teaching. At the end of the training, questionnaires and observations indicated that the student teachers: (1) had more positive attitudes toward teaching; (2) used more indirect teaching patterns in grammar and conversation lessons; (3) had more negative attitudes toward their cooperating teachers; and (4) were perceived more favorably by the pupils in their classes. In a graduate course, in-service teachers were taught three systems: interaction analysis, FLint (Foreign Language Interaction), and IDEI, a nonverbal system. Using these instruments, the teachers analyzed a tape recording of their teaching prior to the course, comparing it with a videotape of themselves micro-teaching partway through the training. Activities were aimed at sensitizing participants to the influence of teacher behavior on students. A questionnaire was sent to the inservice teachers one month after school started to determine whether the course content had affected their on-the-job teaching. Responses indicated that the teachers felt studying observational systems had influenced them to make numerous desirable changes in their teaching, causing them to feel more confident and competent in their classroom interaction.