Past work has linked psychological trauma to problems in romantic relationships and to the quality of social attachment in clinical populations and adult married couples. Little work has focused, however, on late adolescent dating relationships or community samples. Further, no studies have evaluated the extent to which specific behaviors mediate the relation between trauma and relationship quality. The current study evaluated the relation between trauma and relationship quality in a sample of 199 18-21 year-old opposite-sex dating couples. This study also evaluated whether secure base behaviors (i.e., attachment processes) partially mediated the relation between psychological trauma and couples' ratings of perceived relationship quality. While the mediating model was not supported, the relation between trauma and relationship quality was supported in this sample. This finding extends previous work with adult married relationships and clinical populations by demonstrating that higher levels of trauma exposure and symptoms in a community sample of late adolescent couples is associated with negative perceptions of relationship quality. Future directions for developmentally sensitive approaches to the study of trauma and relationships are discussed.