A pivotal issue in research on writing concerns whether the knowledge of how genres are constructed and learned in one discipline/genre can be transferred to other contexts, genres, and disciplines. Yet, studies conducted so far have not presented a unified and complete view of how various writing instructional techniques can result in transferability. This study examined the effect of structuring and problematizing scaffolding mechanisms and the mediating effect of learners’ proficiency level on a cohort of Iranian English learners’ ability to transfer the acquired genre-based knowledge to a new discourse mode. Four groups of thirty pre-intermediate learners chosen from eight intact classes and four groups of advanced learners selected from eight intact classes participated in this study. The performance of the participants in structuring scaffolds, problematizing scaffolds, and combined structuring and problematizing scaffolds conditions were compared to that of the control groups. The results of a two-way ANCOVA revealed that scaffolding mechanisms could significantly result in genre-transferability. The results also suggested that scaffolding mechanisms brought about the best results when offered simultaneously. Besides, the result yielded no significantly moderating effect for learners’ proficiency level. Implications for classrooms are discussed.