Arginine Vasopressin is a peptide hormone critically situated at the intersection between two essential biological responses, stress and social behavior, governed mainly by a single biological substrate, the hypothalamus. The proposed research provides a unique avenue into how AVP plays a crucial role in each both from an anatomical and functional perspective. Chapter 1 introduces historical research focusing on the role of the paraventricular nucleus of the hypothalamus (PVN) and particularly AVP-expressing neurons in the PVN and their connection with homeostatic functioning, the stress response and social behavior. Chapter 2 investigates this region and cell type from an anatomical perspective, employing retrograde synaptic tracing techniques to investigate the connections between AVP-expressing neurons and their afferent inputs. What we discovered is neuronal populations directly connected to these cells stay relatively local in thalamic and hypothalamic areas, but these input regions are known to be involved in several functions including learning and memory, social behavior, pain, feeding and the stress response. We also learned that the inputs that stay within the PVN are mostly non-peptidergic as they displayed relatively little overlap with AVP, Oxytocin (OXT) or Corticotrophin Releasing hormone (CRH). In chapter 3 we focus on the functional role of AVP in the stress response, using the optical technique fiber photometry to measure the neural activity of the global PVN alongside AVP-expressing neurons during different stress paradigms. What we discovered was that while PVN showed consistent patterns of activity during stress and nonstress recovery phases, the AVP-expressing neurons were more nuanced, displaying context dependent activity patterns including strong reactivity when a conspecific was present. In the majority of cases the PVN and AVP signals showed strongly opposite signal patterns. Chapter 4 summarizes these findings in a broader context, offering insights into the results from the perspective of a foundation from which more complex work can be built.