This investigation about teachers’ beliefs tried to find out information about the underlying structure of teachers’ decision making, behavior, classroom practice and classroom management. Teachers’ beliefs have been called the messy construct. Studying this messy construct in Iran is a new field of research. Thus, in this paper, the researcher focused on high school English teachers’ beliefs. The content of beliefs was important for identifying and changing them. For achieving this goal, two questionnaires, IKTS and TABS, were administered to 261 high school English language teachers in Khuzestan province, and the data of the questionnaires were used to cover quantitative section of the research. Qualitative data were collected through semi-structured interviews and observations, to obtain meaningful insights about the beliefs of English teachers. Sixty teachers participated in a semi-structured interview, thirty of whom were randomly selected for classroom observation. By transferring their responses into written form, the researchers found out a number of themes related to teaching, learning, and schooling in the speeches of participants. The themes were discussed in order to disclose the hidden part of the participants’ mind, and consequently their performance in the classrooms. The results of quantitative and qualitative instruments were integrated and discussed to reveal the English teachers’ beliefs maps about the importance of teaching language knowledge and the nature of teaching ability.
