To address the potential of the incorporating of output-based tasks, this quasi-experimental research compared the impact of two kinds of output tasks, namely dictogloss and editing text, on the development of grammatical knowledge of Iranian EFL learners. The study sample consisted 24 female learners studying at the high-school level in Iranshahr, Sistan and Balouchestan Province. They were divided into three groups, each containing 8 participants. The groups under the study were the control group, dictogloss group, and text editing group. The target structure was the passive voice. T-test and post hoc Tukey were utilized for the analysis of the data. The study results advocated the superiority of experimental groups over the control group. Moreover, it was shown that there are no statically significant differences between dictogloss and text editing groups in terms of grammatical development. It was concluded that output-based tasks in the form of dictogloss and editing tasks are beneficial in enhancing the grammatical knowledge of Iranian EFL learners regarding passive voice.
