Today, a new knowledge economy and more service-based offerings are commonly mentioned as a challenge for manufacturing companies. This challenge addresses the companies’ knowledge base and the traditional engineering expertise areas. The report starts from an assumption that there are differences in how knowledge is managed, as well as differences in the intentions to why it is managed. Based on this assumption, the purpose in the report is two-folded. First, the purpose is to conceptualize different facets of knowledge within a framework of technical product development. Second, the purpose is that the report serves as a trigger for discussions and reflections on existing practices in industrial workshops. So, despite that the report does not provide the “right” answers to these questions; they still guide the work in our research:• What is actually managed in every-day engineering project work?• And, for what purposes?The work accounted for in the report comes from a literature review and our jointefforts in understanding the research area from a theoretical perspective. First general views on knowledge is presented, including its classification in different ways, compared to information and data, as well as its division into tacit and explicit knowledge, or practical skills and theoretical knowledge. Human factors, including how people search for information, is also presented. Then a more explicit focus on technical knowledge is presented, showing the shift from knowledge as an artefact to a social and personal perspective in recent years. This also encompasses discussing the capabilities and knowledge of an engineer. A contribution of this report is the conceptualization of different facets of engineering knowledge; especially the more social aspects of engineering knowledge have been highlighted.