Teacher professional identity is widely acknowledged as a multi-dimensional dynamic evolving concept contributing to teachers’ self-perception about their professional roles. This qualitative study aimed to explore how different instructional settings of teaching English as a foreign language in Iran impacted on teachers’ professional identities in a comparative way. To this end, 25 English teachers from public schools and private institutes of Kerman were interviewed to collect data and to examine how teachers conceptualize themselves at schools and institutes. All 25 participants (13 school teachers and 12 institute teachers) had a BA degree in English. Data analysis revealed that teachers of public schools had comprehended, strong, and thick initial professional identity in comparison to those teaching in private institutes. However, such an ideal professional identity was more vulnerable to professional identity shock that resulted from the discrepancy between initial professional identity arisen from pre-service training programs and an emergent one derived from the identity-in-practice in class life. In terms of preparation to teach, the findings showed that the teachers of public schools had more extended viewpoints towards teaching and its significance. Moreover, they believed that their identity influenced the teaching profession while the institute teachers believed in teaching influence on their identity that provided evidence for the variable nature of teacher professional identity resulting from parallel interconnections of different macro and micro factors leading to its steady reinterpretation and reshaping. Keywords: dyna
