Development-oriented design-based vocational research is conducted in research and development arenas in which academics and practitioners engage in a common working environment. The dual aim of this work is to create innovative development products and to gain theoretical insights. Both ofthese arise in the discourse of the actors involved. The subject of the paper is what exactly characterizes this discourse, how new knowledge arises through discursive practices, what kind of knowledge this is and what role the contributions of scientists and practitioners play. Based on discourse-theoretical foundations, the knowledge genesis is investigated discourse-analytically on the basis of a case study of a research and development project