Multiple examples of disciplinary-specific threshold concepts already exist within the academic literature and additional disciplinary-specific threshold concepts continue to be added to this growing list. However, less attention has been devoted to both the identification and understanding of those key threshold concepts that hold such a level of importance that they cross over into multiple disciplines. I maintain that these discipline-crossing threshold concepts require a more complex analysis. Specifically, one must ask: how are interdisciplinary threshold concepts able to retain their core nature while seemingly transforming to conform to the demands of distinctly different disciplines? This paper will be devoted to answering this question by offering a preliminary analysis of the epistemological and ontological nature of interdisciplinary threshold concepts. To further illustrate this emerging theoretical analysis, an interdisciplinary threshold concept is isolated and discussed in relation to the three disciplines that claim it. Finally, I discuss how the lessons learned from this examination will aid in the identification and understanding of other interdisciplinary threshold concepts.