With the latest paradigm shift in SLA from Cognitivism to Sociocultural Theory (SCT), more studies are carried out to investigate the efficacy of Written Corrective Feedback (WCF) through a social and cultural lens. A more recent offspring of SCT is Activity Theory which provides an explanatory framework for scrutinizing an activity in a social setting. The present study aimed at investigating the impact of Scaffolded WCF within the framework of Activity Theory on Iranian EFL learners’ writing performance in terms of reduction of the learners’ writing errors with respect to the content, vocabulary, mechanics, organization, and grammar. Finally, different types of Activity Theory-based strategic mediations (i.e. artifact, rule, community, and role mediations) Iranian EFL learners employed in their writing revisions were investigated. Accordingly, 25 Iranian university-level students, through convenient sampling, were chosen to participate in the study. The treatment they received on their writings was a graduated Scaffolding WCF in their Zone of Proximal Development in the form of both peer and teacher feedback. The findings indicated that Scaffolded WCF statistically significantly contributed to the participants’ writing performance in terms of content, vocabulary, mechanics, organization, and grammar. With respect to the mediation strategies used by the learners, it was discovered that the learners benefitted from all the available mediators although with various degrees. It is hoped that the findings of this study will promise implications for promoting a teacher/learner-friendly method of providing WCF based on SCT, which can be utilized in large classes typical of Iranian EFL university courses.
