This mixed-method study investigated the various competencies English as Foreign Language (EFL) teachers require by examining a model. To fulfill the study objectives, the grounded theory was adopted in the qualitative phase to explore EFL key informants' articulations and concerns about the issue; therefore, semi-structured interviews were conducted with 21 Iranian EFL teachers recruited by purposeful sampling. In the quantitative phase, a researcher-made 103 item questionnaire was extracted based on the interview codes. After being piloted, it was administrated to 382 Iranian EFL teachers to validate the results obtained in the qualitative phase and investigate Iranian EFL teachers' professional competency and their preferences about its dimensions. Three dimensions were discovered in the qualitative phase, which was not favourable among EFL teachers in the quantitative phase. Meanwhile, factor analysis about the EFL teachers' dimensions yielded three factors according to priority: a) attitudinal competency, b) management competency, and c) language competency. The researchers concluded that attitudinal competency is regarded as the most highly valued of the three dimensions by Iranian EFL teachers. Language competency is regarded as the least priority, which justifies the fact that despite showing eagerness and enthusiasm to teach, these teachers do not possess enough linguistic competency and do not tend to develop it. Accordingly, the researchers suggested some practices for developing EFL teachers' professional competency, emphasizing that all dimensions are essential and EFL teachers should have a balanced combination of them. Manuscript profile