The term ‘participation’ traverses the depth-psychology corpus along several distinct but intersecting trajectories. In its most philosophically fundamental register, it appears in Platonic and Neoplatonic discourse as the metaphysical mechanism by which finite entities share in being, time, or form — Plato’s Parmenides subjecting the concept to rigorous dialectical scrutiny, Plotinus extending it into questions of how soul inhabits matter without being diminished by it. David Abram, drawing on phenomenological resources, recuperates participation as a perceptual-ecological category: the act of sensing is always already a form of participation in a more-than-human world, a participation the rationalist stance attempts — always unsuccessfully — to arrest. In the psychoanalytic register, Kalsched mobilizes the term to indicate how unconscious fantasy co-constitutes the meaning of trauma, insisting that neurosis requires the participation of psychic depth, not merely external event. The group-therapy literature, represented most extensively by Yalom, treats participation as an empirically measurable therapeutic variable: degree of member participation in planning and process correlates directly with therapeutic outcome and commitment. The addiction-recovery literature treats participation in 12-step programming as a dose-dependent independent variable mediating abstinence and psychological wellbeing. These registers — metaphysical, phenomenological, psychoanalytic, group-dynamic, and recovery-behavioral — rarely speak directly to one another, yet together they reveal participation as a concept indispensable to any account of how the self is constituted through its embeddings.