Inspired by appraisal theory, the current study looked into the effect of using evaluative language on high- and low-graded post-graduate students' academic writing in an EFL context across male and female groups. Participants were 60 MA students of TEFL who were randomly assigned to experimental (n = 30) and control (n = 30) groups. Attitudinal and Graduation resources of evaluative language were taught to raise the students' critical stance in academic writing. Conventional writing instruction was provided for the control group. The writing pre- and post-test was the main instrument in order to investigate the difference between the students' performance in the study groups. Findings revealed that evaluative language could significantly result in increasing the post-graduate students' academic writing ability, while no significant difference was resulted between the male and female groups. High-graded students were also found to act significantly better than the low-graded ones in writing academically. The results of the study revealed that evaluative language can contribute to the post-graduate students' possessions of critical stance in writing academically, which helps the writer to make a dialogic interaction with the reader.