Abstract The facilitative role of scaffolding has been highlighted by research with empirical evidence on learners’ engagement in classroom interaction and their uptake of teacher instruction but the body of empirical research focusing on genre-based pedagogical approaches for Vietnamese learners as second language (L2) writers remains relatively limited. The present study extends this line of enquiry by investigating how five experienced EFL teachers at two Vietnamese colleges apply scaffolding strategies in genre-based L2 writing classes and how teacher professional development workshops shifted the teachers’ beliefs about such an approach to teaching EFL writing. Data were collected from 30 classroom observations (10 before and 20 after the workshops) and five individual semi-structured interviews with the teachers. A content-based approach was adopted for qualitative data analysis. Findings show that the teachers used a much wider range of scaffolding strategies, with questioning and giving feedback being the most frequently-used strategies, in their EFL writing classes compared to those observed before the workshops. The study further shows that there were remarkable changes in the teachers’ beliefs about genre-based L2 writing pedagogy and that they highly valued the potential impact of this approach on learners’ uptake in writing skills. Implications for second language writing pedagogy and teacher professional development will be discussed.