Since the pioneering work of Bandura (1977), teachers’ self-efficacy defined as teachers’ judgments of their own capabilities to deal effectively with various educational situations and tasks (Bandura, 1986) in context-specific, cognitive, metacognitive, affective and social ways (Wyatt, 2010) has been considered as one of the most central and pervasive thoughts that affect teachers’ actions. This study was an endeavor to explore how a particular teacher training program at a language institute in Tabriz which provided pre-service and in-service teachers with opportunities to practice various pedagogical tasks and also reflect on their own and others’ performance can influence their self-efficacy. To achieve this goal, a quasi-experimental design was adopted. 37 pre-service and 40 in-service teachers participated in the study. The teacher sense of efficacy scale (TSES) was utilized to explore fluctuations in teachers’ self-efficacy. The results revealed that the teacher training program was influential in enhancing the self-efficacy of both pre-service and in-service teachers.