This chapter aims to move intellectual capital (IC) research and practice one step closer toward the development of a foundational theory, which can be used to test scholarly research hypotheses and expound practical organizational strategies that bring about enhanced organizational value and, where appropriate, competitive advantages. The history and research into IC and knowledge management (KM) are examined for possible theoretical foundations since both disciplines initially sprang from similar concerns regarding the part knowledge played in the creation of value by organizations. Such a review demonstrates that there are many considerations that need to be reflected on in any foundational theory of IC. Theories and principles in economics are also explored as they might provide a natural basis for such an IC theory. However, in critically reviewing several Theories of the Firm, it is concluded that they provide a very limited articulation into the part played by knowledge in the creation of value by firms and, by extension, organizations in general. Thus, the conclusion of this chapter is that, at present, there is no adequate theory which explains the process by which organizational knowledge underpins the creation of value by organizations. However, the conclusion is not wholly negative since some possible ways forward are discussed.