This chapter espouses the transformative possibilities of viewing your relationship to yourself as one of “possession.” It affirms “self-possession” (and related reflexive notions including “self-property,” “self-ownership,” “self-appropriation,” and “self-belonging”) as benign expressions of agentic humanism. These conceptions cast the individual conscious sense of self as the active possession of an inner structure of properties, including discrete memories, experiences, qualities, ideas, and values to which one has privileged introspective access. To be self-possessed is to construct and take care to maintain a coherent psychological structure and then rely on it to formulate, motivate, and justify one’s specific thoughts, words, deeds, and interactions with others in the world. This chapter proceeds through three steps: (1) brief consideration of the etymologies of the relevant idiom expressing the concept, (2) substantial attention to the history and contexts of some philosophical exemplars invoking the concept, and (3) suggestive reflection on relevant contemporary psychology and elucidation of nuances in the concept of self-possession for behavioral use in the present. By the end, it is hoped that the reader will better appreciate the transformative possibilities in becoming more self-possessed.