People develop feelings of ownership for a variety of objects, material and immaterial in nature. We refer to this state as psychological ownership. Building on and extending previous scholarship, the authors offer a conceptual examination of this construct. After defining psychological ownership, they address "why" it exists and "how" it comes into being. They propose that this state finds its roots in a set of intraindividual motives (efficacy and effectance, self-identity, and having a place to dwell). In addition, they discuss the experiences that give rise to psychological ownership and propose several positive and negative consequences of this state. The authors' work provides a foundation for the development of a comprehensive theory of psychological ownership and the conceptual underpinnings for empirical testing.