An investigation of the epistemological beliefs of apprentices in the commercial engineering sector is of interest for vocational training, both from the point of view of optimising vocational didactic processes as well as in terms of communicating suitable knowledge based beliefs about principles and performance in the commercial engineering field. This article reports on a seminal study, in which 50 apprentices in the occupational fields: construction, electrical engineering and mechanical engineering were interviewed about their knowledge-related beliefs. The results include explorative data and highlight difficulties encountered during the study.