Nowadays, the goal of language education has changed from mastery of structure to the ability to use language for communicative purposes; however, the cultural content of the ELT textbooks in Iran has never been sufficiently discussed. Therefore, the major purpose motivating this study was to study the perceptions of teachers and learners of the localization of Iranian English textbooks in the Iranian EFL textbooks (i.e., Prospect series), besides investigating if there were any significant differences between the perceptions of teachers and learners. For this purpose, the participants of this study comprised two samples. The first group who took part in this study were 87 EFL teachers, and the second was a sample of 105 EFL learners. The research instruments were a questionnaire and a semi-structured interview protocol. For the evaluation of the textbook, a researcher-made questionnaire was used. The questionnaire was designed based on Cheng (2005). The purpose of this questionnaire was to probe the Iranian EFL teachers' and students' perceptions of the localized materials. In order to explore teachers' attitudes towards localized materials, a semi-structured interview was used. The findings suggest that while teachers and learners might view the series differently, there exists a common ground of appreciation for its value in enhancing the English learning experience. This convergence in positive perceptions emphasizes the importance of educational resources that cater to diverse learning styles and preferences. This study can have some pedagogical implications for curriculum developers, educational policymakers, teachers, and material designers. تفاصيل المقالة