Thesis advisor: John P. Christianson / The perception of others as safe or threatening informs how we respond to others in a social setting. These social affective behaviors require the detection of sensory stimuli and the appraisal of others’ affective states to orchestrate adaptive behavioral responses. This process is also informed by one’s own internal state and environment. The neural circuitry underlying this behavior consists of a wide network of brain regions that communicate to execute social behaviors. However, the neural mechanisms mediating social affective behavior require further investigation. Therefore, the objective of this dissertation is to add detail to our understanding of the specific brain circuits involved in social affective behavior. The insula is a key node within this circuitry, necessary for approach and avoidance behaviors in a social affective preference (SAP) test where adult rats prefer interactions with stressed juveniles but avoid interactions with stressed adults. Here, I investigated the roles of a basolateral amygdala projections to the insula and insular projections to the PL in SAP testing and present evidence indicating the necessity of both these tracts to social affective behaviors. The results described here along with the reviewed literature support a potential amygdalar-insular-prefrontal circuit responsible for detecting social valence, integrating external stimuli with internal states, and selecting and executing context-appropriate social affective behaviors. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology and Neuroscience.