In an attempt to shed light on how expert teachers of English language are distinguished from non-experts, the present research explored how pedagogical content knowledge, as a characteristic of experts relates to four other dimensions of expertise in ELT. These include teacher’s experience, cognitive skills, professional development and learner-centered teaching. To this aim, a questionnaire was developed based on the related literature, comprising 109 items, 41 of which enquired about pedagogical content knowledge and the rest about the other dimensions of expertise in ELT. The reliability and validity of the test were confirmed. The SEM analysis results showed that pedagogical content knowledge was positively and significantly correlated with teacher’s experience, cognitive skills and learner-centered teaching. It also showed to have a statistically significant causal relationship with professional development. The findings proved the significance of pedagogical content knowledge as a prominent feature of expertise in ELT, which requires attention to teacher’s lesson planning, class management, problem solving, learning assessment/feedback and task design in teacher education programs or teacher evaluation program especially for the sake of teacher professional development.
