This chapter seeks to develop a view of design as a discipline based upon a science of design, but not a ‘design science’. It begins by unravelling some of the history of concern with relationships between design and science, and distinguishes between scientific design, design science, and a science of design. It argues that the underlying axiom of the discipline of design is that there are forms of knowledge peculiar to the awareness and ability of a designer. The latter part of the chapter outlines the ways in which this discipline of design, and the understanding of designerly ways of knowing, can be pursued through design research. Three sources of design knowledge are identified as research loci: people, processes and products, implying three fields of research—design epistemology, design praxiology, and design phenomenology. These are the foundation stones for understanding designerly ways of knowing and thinking. The chapter concludes by outlining the characteristics of good research, applicable in any disciplineDesign discipline.