Competency-based education (CBE) has been widely adopted in various educational contexts although research discussing how CBE is implemented in local contexts and how it shifts (or not) teaching practices is limited. This study explores how Vietnamese secondary teachers made sense of general competencies and adapted their teaching towards competency development. Using a sociocultural approach to sensemaking, this study examined secondary teachers' interpretations and teaching practices of competencies. The study used a qualitative longitudinal design that included teacher interviews and video-cued reflections of their teaching practices. The findings illustrate teachers' ambivalence about the new curriculum competencies and how to align their practices with the CBE reform. A common pattern across all teachers was that they made sense of competencies as learning foundational knowledge and skills, in addition to developing good attitudes, character, and morality. Over the years, teachers also emphasised the real-life application of competencies towards whole-person development. This study contributes to sociocultural perspectives on teaching and the CBE literature by showing the ways in which teachers used cultural ideas and artefacts to expand and limit their meanings of competencies in practice.