The ventral vagal shift designates the movement of the autonomic nervous system from states of sympathetic mobilization or dorsal vagal collapse into the ventral vagal state of safety, social engagement, and regulated connection — the apex of the polyvagal hierarchy. Within the depth-psychology corpus, the term is treated not as a discrete neurophysiological event but as a clinical and phenomenological process with profound therapeutic implications. Stephen Porges supplies the foundational neuroscience: the ventral vagal circuit, originating in the nucleus ambiguus and mediated by myelinated vagal fibers, provides rapid, organized inhibition of sympathetic activation and enables the social engagement system. Deb Dana translates this substrate into clinical technique, elaborating the ventral vagal shift as the telos of polyvagal-informed therapy — the destination toward which mapping, pendulation, co-regulation, savoring, and somatic exercises are all directed. Dana’s corpus insists that the shift is rarely volitional; it requires the therapist’s own sustained ventral vagal presence as a co-regulatory scaffold, and it proceeds through micro-moments — ‘glimmers’ — of safety before consolidating into durable regulation. Key tensions include whether the shift is most reliably achieved through top-down (narrative, cognitive) or bottom-up (somatic, postural, respiratory) interventions, and whether interactive or self-regulatory pathways represent the more reliable route for trauma-shaped nervous systems. The shift is understood as both endpoint and ongoing practice.