Engineering encompasses a range of activities focused on systematically designing products and solving problems. While different branches of engineering have distinct traditions and approaches, they share a common foundation in methodology and in an instrumentalist attitude. One of the Swedish upper secondary school programmes is called the technology programme. It provides students aged 16–19 with an education in the fundamentals of engineering. The curriculum is intentionally broad, allowing schools and individual teachers significant flexibility in selecting content and teaching methods. Many teachers in the technology programme are former engineers who have made a transition into teaching. The influence of these teachers in shaping the educational experience is palpable through the application of their engineering background. They bring knowledge, skills, and professional values from their engineering careers and education into the classroom, which often results in their prioritising familiar areas of expertise. While enhancing the depth and authenticity of their teaching, this also risks introducing substantial variation in content, relevance, and quality of instruction across different schools. In this study, 13 of these engineer-teachers were interviewed about their teaching practices and perspectives regarding engineering subjects. Responses  were analysed using Étienne Wenger’s Communities of Practice (CoP) framework. From this analysis emerges a complex practice whereby engineer-teachers’ deep commitment to the ideals of engineering thought and practice gains in importance, underlining the perceived necessity of reflecting that vision in their teaching.