Recently, the sources of teachers’ beliefs and modifications in their beliefs have received special attention; therefore, this longitudinal study investigated Iranian EFL teachers’ pedagogical beliefs. The study attempted to track possible alterations in pedagogical beliefs after participating in a two-year teacher training program and following teaching practices. Through convenient sampling, the researchers selected 24 Iranian EFL teacher students who had teaching experiences of 3-10 years at Islamic Azad University; Shiraz Branch. They collected the required data through a teacher belief questionnaire and a semi-structured interview. The results of both quantitative and qualitative data indicated that teaching practices made a unique influence on the modifications in teachers’ pedagogical beliefs. In other words, the results emphasized the power of teaching practice in any modification in teachers’ beliefs over theoretical teaching. These findings have important implications for teacher educators who seek to modify teachers’ beliefs during teacher training programs. Manuscript profile