A growing body of research has acknowledged the contributing role of teachers’ sense of efficacy in enhancing their optimal performance in the classroom. In spite of the incremental appeal of teacher self-efficacy in educational investigations, the majority of studies investigating the effects of teacher’s efficacy beliefs have primarily focused on its relations with teacher-related variables and few studies have investigated its contribution to improving students’ language achievement especially in EFL context. To address this gap, the purpose of this study was to examine the relations between Iranian EFL teachers’ self-efficacy beliefs and language achievement among their students. Students’ language achievement was measured through standardized achievement test scores. The participants of the current study included 43 practicing EFL teachers and their students (n=542). Teacher self-efficacy scale was administered to the practicing teachers and the students’ scores on the achievement test were considered as the students’ outcome variable. To analyze the collected data, doubly latent multilevel structural equation models were employed to achieve a proper disaggregation of the processes occurring at the classroom, versus individual student level. The results demonstrated direct positive relations between teachers’ sense of efficacy and the class average of standardized achievement test scores. The findings offer theoretical and practical implications for EFL teacher education.