Design Science is establishing as a major IS research perspective. As journals and conferences have taken up the Design Science stream, such situation offers great potential to frame, to improve, and to publish design-oriented research. Several endeavors have already been undertaken in order to conceptualize and apply Design Science, however, we still find key questions that are not yet answered in the prominent IS literature. A very central one is that of the role of kernel theory in Design Science. In the course of my talk, I will provide an overview over arguments in IS literature on what design theory is, on what kernel theory is, and on how these theory types related to each other. I will thus try to elucidate a Design Science perspective on the scientific process of knowledge creation and attempt to provide some practical advice for building design theory.