The purpose of this study is to investigate the effects of task-based instruction (TBI) and project-based instruction (PBI) on the improvement of EFL learners' referential and expressive writing performance. To accomplish this objective, 60 students majoring in English translation participated in Oxford Quick Placement Test (OQPT), but out of them 50 students were selected as the members of a homogeneous sample. Then, they were assigned into two experimental groups. They were exposed to IELTS module task-based writing pre-test, treatment, and post-test, to assess the participants' writing performance. The participants in first experimental group received TBI to practice the referential and expressive types of writing, while those in the second group received PBI. The results showed that TBI and PBI affected the development of both referential and expressive writing among EFL learners. In addition, the results revealed that there was not any statistically significant difference between the effect of PBI and TBI on developing expressive and referential writings among EFL learners. The pedagogical implications of the study are discussed at the end of the paper. Manuscript profile

L2/FL writing ability, which per se includes many different types, is considered a major skill in academic settings. However, little research has been done in this area and even less has focused on the effectiveness of task-based writing instruction on the two specific kinds; namely, referential writing and expressive writing. To this end, 60 English Translation sophomores of both genders were selected and divided into two classes after ensuring their homogeneity through the Quick Placement Test (OQPT). For the pre- and post-tests, the participants were required to take IELTS writing tests requiring referential and expressive types of writing. As for the treatment of the study, all participants were instructed based on the same content materials of advanced writing and a task-based framework. The results of the statistical analysis indicated significant improvements in the participants’ writing abilities in referential and expressive written tasks. Besides, the effectiveness of task-based writing techniques was approved in terms of referential and expressive types of language functions in the academic writing of Iranian EFL learners. Manuscript profile