The aim of this study is to reveal the English teachers’ self-efficacy perceptions of the teaching process and how they apply these self-efficacy skills in the classroom environment. In the research the exploratory sequential design, which is one of the mixed method designs was used. In the first stage of the research, English teachers’ self-efficacy perceptions were determined according to gender and occupational seniority variables and the level of their self-efficacy perceptions were presented. In the second stage, the teachers’ performances were observed in the real class environment within the context of the case study. 406 English teachers who worked in Elazığ province in the spring semester of 2016- 2017 academic year constituted the working group of the first phase of the study. After the analysis of the first stage, the study group for the second stage was determined among teachers whose self-efficacy levels were below the average, mid-level and above the average, and nine volunteer teachers who have different levels of self-efficacy were observed in class environment. In the study, to determine English teachers’ perceptions about their self efficacy perceptions on teaching process "Teacher's Self-Efficacy Scale" (TSES) adapted to Turkish by Çapa, Çakıroğlu and Sarıkaya (2005) was used. In order to observe the teaching practices in the classroom a structured observation form was used. In the research the MannWhitney U test was used in the analysis of gender; to compare the English teachers’ opinions with occupational seniority groups Kruskal Wallis H test was used. Data obtained from structured observations were analyzed by descriptive analysis method. As a result of the research; it was found that there are some differences between English teachers’ self-efficacy levels for the teaching process and their teaching practices in the class.