The current study investigates the effect of self- and group-reflection training on Iranian in-service EFL teachers’ performance development. From all available participants teaching at the International College of Tehran University of Medical Sciences, 40 in-service EFL teachers were selected. An observation checklist, a semi-structured interview, and the Skype app were employed. There were two groups, i.e., a self-reflection group (N=20) and a group-reflection group (N=20; five subgroups with four members). A mixed-methods design was used in this study. Before the training phase, the pre-test (observation checklist) was administered. During the training phase, the self-reflection group members were exposed to self-reflection practice. In addition, the group-reflection participants were exposed to the group-reflection practice. The instruction was presented in 16 sessions twice a week for two months. After the training phase, the post-test (observation checklist) was administered. Moreover, participants were given a semi-structured interview on their reactions to their teaching efficacy. The obtained data were analyzed through SPSS software version 23. The analysis of data revealed that implementing the principles of self-reflective and group-reflective instructions had statistically significant effects on Iranian in-service EFL teachers’ teaching performance. Also, participants believed that reflective practice in both forms had constructive effects on their teaching performance. This study has pedagogical implications for English language teachers, EFL learners, and teacher educators who seek to find more effective teaching methodologies and help them to construct their own meaning of teaching. Manuscript profile

This study examines the effect of implementing group-reflection training on Iranian in-service EFL teachers’ beliefs and performance development. From all available participants teaching at the International College of Tehran University of Medical Sciences in Tehran, 20 in-service EFL teachers participated in this study. All participants held a master's degree in TEFL. Teacher’s belief questionnaire, observation checklist, and Skype app were used as the instruments to collect data in this study. Before the training phase, the pre-test (observation checklist) was administered, and teachers’ previous teaching performance was evaluated and recorded by an expert supervisor (one of the researchers). Also, the teacher’s belief questionnaire was used by all the participants in this study to evaluate teachers’ assumptions about the efficacy of their teaching practice. The researchers utilized Skype App to instruct the participants in an online setting. During the training phase, participants were exposed to the group-reflection practice. The instruction was done in 16 sessions twice a week for two months. After the training phase, the post-test (observation checklist) was administered, and teachers’ teaching performance was evaluated and re-recorded. The teacher’s belief questionnaire was also utilized as the post-test. The data analysis indicated that implementing the principles of group-reflective instruction had a statistically significant effect on Iranian in-service EFL teachers’ beliefs about their teaching efficacy and teaching performance development. The findings of the present study have some implications that can assist English language educators, EFL learners, students, language curriculum program policymakers, and syllabus designers. Manuscript profile