The present study strove to examine the extent to which English teachers’ affective factors including their work engagement, teacher reflection, self-compassion, professional identity, emotion regulation, and grit predicted their productive and maladaptive teacher immunity in the contexts of Iran and Canada. Moreover, it investigated the differences between Iranian and Canadian language instructors’ immunity. To this end, first, the researchers selected 632 Iranian and 593 Canadian teachers in language school settings using convenience sampling. Second, they administered seven reliable and valid questionnaires concerning the aforementioned affective factors to Iranian and Canadian participants to collect the data. Lastly, they analyzed the data using Binary Logistic Regression and Chi-square tests. The results showed that while Iranian teachers’ work engagement, emotion regulation, and grit were the significant factors in their teacher immunity types, Canadian teachers’ teacher reflection, professional identity, self-compassion, and emotion regulation significantly predicted their productive and maladaptive teacher immunity. Furthermore, Canadian teachers’ immunity was more productive than that of Iranian teachers. These results may provide guidelines on the development of teacher-factor-informed education courses for English teachers in both second and foreign language contexts.