Within the depth-psychology corpus, ‘capacity’ operates as a term of both developmental achievement and clinical horizon: it names what the psyche can do, what trauma has foreclosed, and what therapeutic work must restore. The term appears across several distinct registers. In object-relations tradition, most luminously in Winnicott, capacity designates a developmental attainment — the capacity to be alone, the capacity for concern — each marking a stage in ego-integration made possible only within a sufficiently protective relational environment. In trauma theory, particularly in the sensorimotor lineage of Ogden and the somatic work of Levine, capacity refers to integrative function: the ability to tolerate, modulate, and metabolize affective and autonomic states without dissociation. Here ‘integrative capacity’ and ‘window of tolerance’ are mutually constitutive constructs, and the restoration of capacity becomes synonymous with the goal of trauma treatment itself. Schore and developmental neuroscience ground capacity in dyadic affect-regulation, tracing self-regulatory capability to early maternal attunement. In Taoist philosophical psychology, innate capacity (as opposed to conditioned or artificial capacity) signals the primordial endowment that superior persons preserve and inferior persons lose. Across these registers a common tension persists: capacity as given endowment versus capacity as relational achievement, and capacity as present resource versus as therapeutic aspiration.