Recently, researchers and scholars have come to a consensus that developing academic writing has become a challenge to EFL students. However, less emphasis is placed on the social and situated perspective of writing which allows students to cope with the demands of producing their proposals effectively, considering the purpose, audience, and context. The current study, therefore, aimed at examining the effect of using different interactive and interactional metadiscourse markers to enhance postgraduate English majors' academic writing skills and self-efficacy. To fulfill this purpose, 60 postgraduate students enrolled in the second-year diploma program, EFL Curricula and Instruction were selected as the study sample. This sample was selected since students, at this year, need to develop their skills of writing academic materials, especially writing thesis proposals. Following a quasi-experimental design, the study comprised two groups: An experimental group (n=30) and a control one (n=30). To obtain data, a pre-post academic writing skills test and a writing self-efficacy scale were designed to measure students' level before and after the treatment. Findings revealed that the experimental group students outperformed their counter peers in the control one in overall academic writing skills, except for "mechanics" where the difference was not significant. Additionally, the experimental group had significantly positive results in the self-efficacy scale compared with the control group.