This investigation examined English as a foreign language (EFL) teachers' perceptions of their self-efficacy in using instructional strategies in the context of the Mekong Delta of Vietnam. The research was designed as a descriptive research collecting quantitative and qualitative data from a questionnaire and semi-structured interviews. Forty-six Vietnamese EFL teachers were invited to partake in the study. The results indicated that participants were in general confident in using instructional strategies in their English classes. Specifically, the participants were highly confident in their abilities to use multimedia (M=4.41), assessment techniques (M=4.35), and classroom English (M=4.35). The study also indicated that participants were not confident in evaluating the level of task difficulty (M=3.37), dealing with unmotivated students (M=3.57), and meeting students' particular needs for support (M=3.62). Pedagogical implications and recommendations were addressed to help manifold stakeholders at the end of this paper.