Invitational Theory is rooted in three theoretical foundations, the perceptual tradition, self-concept theory, and a democratic ethos (Purkey, Novak, and Fretz, 2020). This essay focuses on the second of these foundations, Self-Concept Theory. Self-Concept Theory provides a theoretical foundation for understanding the nature and impact of each individual’s most fundamental perception, the perception of self, or their self- concept. In this essay the author seeks to re-introduce the Invitational community to this important theoretical foundation, which could profoundly and positively impact the enacting and application of invitational theory. All human behavior is fundamentally shaped by how the individual perceives themselves. The author begins by providing an overview of self-concept theory, exploring some of the central tenets and implications. The author then reviews the history of the development of the theory, followed by a summary of some of the theory’s foundational elements. The essay concludes with an exploration of several potential implications and applications for the Invitational community.