The purpose of this study was to explore the relationship between three teacher-related variables, namely, teaching efficacy, institutional identity and motivational strategy use, with students' L2 achievement. The study further intended to pinpoint gender differences in each of the aforementioned teacher-related variables. To this end, 120 (60 male and 60 female) EFL teachers took part in the study by completing Teacher Efficacy Scale (Tschannen-Moran & Hoy, 2001), Institutional Identity Scale developed by Azimi (2012), and Motivational Strategy Use Scale developed by Cheng and Dornyei (2007). Furthermore, the final class outcomes of the teachers' students (n=2045) were collected. The participants were EFL learners and their teachers. The results of Pearson Correlations indicated that there existed significant and positive relationship between the three aforementioned teacher-related variables of EFL teachers and their students' L2 achievement. The results revealed that EFL teachers' efficacy, institutional identity and motivational strategy use had a significant and positive relationship with their students' L2 achievement. A Significant difference was found between the male and female EFL teachers. Also, Motivational strategy use was the strongest predictor of Iranian EFL students' L2 achievement. Based on the findings of the study, a number of pedagogical implications could be recommended. The findings will provide rational support for proposing that EFL teachers should invest in improving their knowledge of teaching efficacy, institutional identity and motivational strategy use.