Due to the pure novelty of the concept of teacher L2 grit, scant research attention has been dedicated to the exploration of its antecedents within the domain of foreign language education. Therefore, the present study aimed to explore whether English as a Foreign Language (EFL) teachers' L2 grit could be predicted by their sense of self-efficacy and self-regulation. Data, collected through three electronic questionnaires from 350 Iranian EFL teachers, were analyzed through structural equation modeling (SEM). The results of SEM analysis indicated that EFL teachers' self-regulation and self-efficacy significantly contributed to their L2 grit. In addition, the findings revealed that EFL teachers' self-efficacy was a stronger predictor of their L2 grit than their self-regulation. Moreover, the results suggested that EFL teachers' L2 grit could be influenced by their adaptation of self-efficacious and self-regularity strategies to maintain their determination and passion for the profession. Finally, implications were discussed and suggestions for future research were offered.