This chapter presents a reflection on the nature and role of knowledge in creative and practice-based research (PBR). It begins with a brief historical overview of the development of PBR, especially in the creative disciplines, how the need for PBR arose, and the challenges associated with it. The discussion highlights how the requirement for explicit or propositional knowledge in research required new practice-based methods and approaches to be introduced to enable the use and recognition of knowledge rooted in practice, called tacit knowledge. This leads to an examination of tacit knowledge in relation to skills and expertise, using two examples, to better understand the role of tacit knowledge in the act of knowledge creation. The discussion of examples reveals further dimensions of knowledge, which necessitate a review of the foundations of traditional understandings of knowledge from philosophical perspectives. The discussion proposes a new framework to relate the different types of knowledge. The conclusion is that there is no issue, in principle, with including tacit knowledge in research, but there remains a tension between the exclusive use of tacit knowledge and requirements of justification in research as well as practical application.