Purpose: This study aimed at investigating the effect of competency-based approach on enhancing complexity, accuracy, and fluency of writing of pre-service teachers. Methodology: To this end, an Oxford Quick Placement Test (OQPT) was administered to 100 Iranian pre-service teachers studying at Farhangian University, of whom 40 upper-intermediate learners were selected and assigned to an experimental group (n = 20) and a control group (n = 20). The selected participants were both male and female and aged from 19 to 22. Both selected groups were then given a writing test as the pre-test. Subsequently, the experimental group received the competency-based treatment and were proposed to some real-world issues and there was no time limit. However, the traditional styles used for improving the writing skill of the subjects in the control group and a specific time limit was considered for the subjects to do the job. After that, a writing post-test and an attitude questionnaire were delivered to the participants. The obtained data was analyzed using one-way between group analysis of covariance (ANCOVA) and one-sample t-test. Findings: The results indicated no significant difference between pre-test and post-test scores of the control group, whereas, the post-test scores of the participants in experimental group were significantly better than their pre-test scores especially regarding complexity. Conclusion: The findings suggest that the teachers should take competency-based approach into consideration in their target language classes to have a more fruitful educational process.
