Iran's latest ELT curriculum reform began in 2013 and was completed in 2019. The reform has had a significant impact on various aspects of instruction, but one of the most important aspects was the teachers' cognition as implementers of the reform. The concept of teacher cognition encompasses a wide range of issues related to teaching, including the classroom environment, contextual factors, and professional coursework. Yet, little was known about the cognition of EFL teachers in relation to curriculum reform. The purpose of this study was to examine how teachers' cognition is influenced by the curriculum reform process. Due to the qualitative nature of this research, a semi-structured interview was conducted to gather pertinent information regarding this issue. The researchers analyzed the collected data to identify the most relevant findings. The findings suggest that the curriculum reform was largely successful in its implementation, with teachers' cognition demonstrating its effectiveness; however, some deficiencies exist. The reform also prompted a transformation in teachers' cognition, necessitating them to update their knowledge and enhance their language skills. The findings provide practical implications that can be used to improve curriculum planning, instructional design, and the facilitation of successful curriculum reform processes
