The purpose of this study was to examine the predictive value of PTSD symptoms and perceived relationship safety on dyadic adjustment. Participants included 390 individuals who were in a committed romantic relationship. Data were gathered from two populations; clients of a university-based family therapy clinic (n = 132), and community respondents to an announcement on a large university's electronic bulletin board (n = 258). Structural equation modeling was used to test a model of mediation, as well as multiple group analysis to test for moderation by setting (clinical vs. community) and gender. Results indicated that perceived relationship safety fully mediated the relationship between PTSD symptoms and dyadic adjustment. Gender moderated the relationships in the model, but no differences were found between the clinical and community samples. Findings suggest the importance of addressing experiences of safety and security in relationships, as these may be of particular importance for those who have experienced trauma.