To explore the effectiveness of flipped instruction in influencing second language learning outcomes, the current research investigated the contribution of flipped classrooms of an English-as-a-Foreign-Language (EFL) writing course to Iranian learners’ writing development and writing motivation. In so doing, two intact classes were chosen as the participants (N=43) of this research and they were randomly assigned to a Control Group (N = 18) and an Experimental Group (N = 25). During one semester, the Control Group underwent the traditional writing instruction, while the Experimental Group received a flipped writing instruction. Second Language Writing Motivation Scale (SLWMS) and two timed writing tasks were given to gather the required data. The results demonstrated that the flipped method of teaching was substantially effective in improving the L2 writing performance of the experimental group (F=22.20, p = 0.000, partial eta squared = 0.35). Also, the results indicated that the flipped instruction had a statistically significant effect on learners’ writing motivation (F= 51.67, p = 0.000, partial eta squared = 0.56). The findings have remarkable implications for L2 writing methodology.
