This chapter discusses divisions of knowledge and distributions of authority within design projects. The aim is to contribute to design research by developing concepts and methods for studying designers at work. By drawing on Science and Technology Studies (STS) we argue that the production of knowledge and authorship in science and design proceed through translation and inscription, though their products differ. Based on a selective review of STS studies of scientific work and studies of architects we develop this point and propose that knowledge and authorship designate two different ‘regimes’, and that the regime of authorship most prominent in the discourse of architects foregrounds narratives of identity and the biographic trajectory of the designer, whereas the knowledge regime closely associated to discourses of scientific work foregrounds knowledge transfer at the expense of subjective involvement. We bring these perspectives to an analysis of a case study of design practice in a rubber valve factory in Denmark. One may query whether our case study is a study of design. It may look more like engineering, or even production. We believe this is not important because clearly, design is being done. The argument in this paper is exactly that design does not appear in pure form, but is embedded in other kinds of activity. The case study thus is an instance of designing as part of product development in industry. We suggest that the case study points to a middle ground of heterogeneity where both regimes of knowledge and authorship are put into play.