How engineers know, and act on that knowledge, has a profound impact on society. Consequently, the analysis of engineering knowledge is one of the central challenges for the philosophy of engineering. In this article, we present a thematic multidisciplinary conceptual survey of engineering epistemology and identify key areas of research that are still to be comprehensively investigated. Themes are organized based on a survey of engineering epistemology including research from history, sociology, philosophy, design theory, and engineering itself. Five major interrelated (...) themes are identified: the relationship between scientific and engineering knowledge, engineering knowledge as a distinct field of study, the social epistemology of engineering, the relationship between engineering knowledge and its products, and the cognitive aspects of engineering knowledge. We discuss areas of potential future research that are underdeveloped or “undone.”. (shrink)