This study proposed a three-step writing conference in which foreign/second language (L2) students, under the guidance of their writing instructor, first fastened their attentional focus on a form-related error, analysed a collection of standard L2 samples to deduce the underlying knowledge, and then planned for their error correction as well as future learning of this knowledge. The ultimate goal of this formative assessment practice was to scaffold student engagement with written corrective feedback (WCF). Using a between-group experiment design, the present study compared the effects on the success rate of error correction and L2 uptake of the above writing conference (n = 14) against those brought about by a typical Teacher-Student (n = 12) and a typical Student-Student one (n = 12). Research participants were 38 intermediate learners of English as a Foreign Language (EFL) recruited from three intact classes at a language-learning center in Vietnam. The suggested writing conference was indeed found to yield better error correction and L2 uptake than the other counterparts. A closer look at the students' mental engagement with WCF revealed that such engagement was moderately correlated with their L2 uptake. These findings altogether suggest that student engagement with WCF should not be taken for granted or, in other words, this engagement should be contingently supported by the writing instructor in order to foster learning from WCF.