This study investigated the dynamism of English as a foreign language (EFL) teachers' professional identity with respect to their commitment and job satisfaction. A mixed-methods design integrating quantitative and qualitative approaches was used. To conduct the quantitative part of the study, 198 EFL teachers were selected from different private language institutes in Mashhad, a city in northeastern Iran. They were requested to complete a battery of three questionnaires. For the qualitative part of the study, four EFL teachers were chosen to be interviewed. Teacher professional identity measured six factors: Self-expectation (SE), Teachers' duties (TD), External influential factors (EF), Pedagogy (PE), Instructional skill and knowledge (SK), Teachers' citizenship behavior (CB). The results of structural equation modeling (SEM) demonstrated that job satisfaction played a positive and significant role in SE and TD. Job satisfaction was in turn influenced by EF. Job satisfaction predicted teacher commitment both directly and indirectly via its effect on TD and CB. Teacher commitment, on the other hand, impacted on PE, CB, and SK. The results of the qualitative part demonstrated the overlap between the three constructs and were in line with the results of the quantitative part of the study.