Due to the novelty of the concept of L2 teacher grit, identifying its determinants has been less explored. In addition, in spite of a growth in positive psychology in language studies, scant research attention has been paid to the notion of L2 teacher resilience. Inspired by the tenets of positive psychology in the field of foreign language education, the present study aimed to investigate whether English as a foreign language (EFL) teachers' grit could be influenced by their work engagement and resilience. Survey data was collected from 380 EFL teachers in the context of Iran. The results of SEM analysis revealed that L2 teacher resilience and work engagement contributed to EFL teachers' domain-specific grit. In addition, teacher engagement was identified as a stronger predictor of L2 grit. The results implied the importance of enhancing teachers' strengths to help them remain passionate and determined throughout the career. The findings suggested the critical role of positive psychology in language teaching research. Suggestions for future research were offered.