The present study investigates affective factors which affect primary English teachers' professionalism. For the analysis of the study, quantitative data was obtained from 576 primary school English teachers who responded to a questionnaire. Qualitative data was also collected from three different focus group interviews and ten individual interviews. A quantitative data analysis shows that collective teacher-efficacy is the best predictor of primary school English teachers' professionalism among the three factors of self-efficacy, organization-based self-esteem, and collective self-efficacy. This result is consistent with interview data which shows that more positive than negative comments are observed in regards to collective teacher-efficacy. Pedagogical implications have been discussed.