Affect tolerance designates the capacity to consciously experience, sustain, and modulate affective states without recourse to dissociation, somatization, or behavioral discharge — a construct that occupies a pivotal position across neurobiological, developmental, and trauma-clinical branches of depth psychology. Allan Schore grounds the concept firmly in neurobiological ontogeny, drawing on Krystal’s (1988) formulation to argue that affect tolerance is an experience-dependent achievement of the right-hemispheric regulatory system, consolidated through the dyadic mirroring processes of separation-individuation and indexed by the individual’s ‘affect array.’ For Schore, broadened affect tolerance signals successful autoregulation and marks the expansion of the self as a psychosocial system. Within trauma theory, Pat Ogden, Daniel Siegel, and their collaborators reframe affect tolerance structurally through the ‘window of tolerance’ — a bandwidth of arousal within which integrative, cortically-mediated processing remains available; states beyond this window collapse into either hyperarousal or hypoarousal, foreclosing the very capacity for affective experience that tolerance requires. Clinical writers from Courtois to van der Hart embed affect tolerance in phase-oriented trauma treatment, positioning its cultivation as the prerequisite for memory processing and developmental repair. The term thus bridges neuroscience, object-relations thinking, and somatic psychotherapy, revealing a shared assumption: that the self’s regulatory architecture must be built, or rebuilt, before affect can be borne.