Since technology education is, compared to subjects such as mathematics and science, still a fairly new subject both nationally and internationally, it does not have an established subject philosophy. In the absence of an established subject philosophy for technology education, one can draw on other disciplines in the field, such as engineering and design practice, for insights into technological knowledge. The purpose of this study is to investigate the usefulness of an epistemological conceptual framework chiefly derived from engineering, to be able to describe the nature of technological knowledge, in an attempt to contribute towards the understanding of this relatively new learning area. The conceptual framework was derived mainly from Vincenti's ("What engineers know and how they know it." Johns Hopkins University Press, Baltimore, 1990) categories of knowledge based on his research into historical aeronautic engineering cases. Quantitative research was used to provide insight into the categories of knowledge used by students at the University of Pretoria during capability tasks and included an analysis of a questionnaire administered to these students. Findings suggest that the conceptual framework used here is useful in technology education and that the categories of technological knowledge apply to all the content areas, i.e. structures, systems and control, and processing, in technology education. The study recommends that researchers and educators deepen their understanding of the nature of technological knowledge by considering the categories of technological knowledge presented in the conceptual framework.