Abstract Literature review confirms that TBCOA and ST were effective in improving EFL learners’ writing skills. However, a new study is necessary to compare the rate of effectiveness of these activities and techniques on Iranian intermediate L2 learners' writing performance. Moreover, the impact of two types of TBCOA versus two types of ST on intermediate EFL learners' writing performance was compared. This research followed a quasi-experimental design. A sample of 80 intermediate-level EFL learners, selected through convenience sampling from a private language school, constituted the participants. The learners were divided into four groups. The homogeneity of the participants in terms of writing performance was checked through a quick placement test at the outset of the study. Furthermore, the effects of debating vs. dictogloss., teacher scaffolding vs. peer scaffolding, and overall TBCOA vs. overall ST were compared through ANCOVA, with the pretest scores treated as the covariate. Debating outperformed dictogloss, teacher scaffolding was more effective than peer, and the overall TBCOA group significantly performed better than the general ST group in writing performance. The learners' interview results concerning the role of TBCOA and ST in their writing production resulted in several common themes, which were categorized into 16 codes for debating, 11 codes for dictogloss, six common codes for teacher scaffolding and peer scaffolding. This study provides implications for EFL writing instruction. تفاصيل المقالة