Objective: Though family of-origin aggression (FOA) is a known risk for later emotional and physical problems in adulthood, little is known about how early exposure to aggression influences physiological reactivity in the domain-specific context of family conflict experienced as an adult. This study investigates whether report of FOA influences spouses’ hypothalamic-pituitary-adrenal (HPA) axis responses during conflict discussions with their family of-procreation and also whether current hostilities, observed during a family discussion, moderate those responses. Method: In a sample of 91 families, we measured parents’ HPA responses through salivary cortisol total output and discussion-related increase surrounding 15-min hot-topic discussions that trained observers coded for family members’ hostility. Partners’ also reported on 8 items assessing parent-to-child and interparental FOA. Results: In models testing within-partner and across-partner influences, wives’ higher FOA was linked with increases in their own and their husbands’ cortisol. Spouses’ own FOA showed significant interactions with the partners’ hostility to affect total cortisol output, although in an attenuated direction for wives and a heightened direction for husbands. Conclusion: The results suggest that HPA responsiveness can elucidate links between family of-origin experiences and adult intimate relationships and may be a factor in risk and resilience over time. (PsycINFO Database Record (c) 2016 APA, all rights reserved)