Borderline symptoms are thought to emerge from the interaction of temperamental factors and environmental stressors. Both parental invalidation and attachment disorganization have been hypothesized to play an etiological role. However, to date the quality of parent-child interaction has not been observed directly. In this study, 120 young adults were assessed for features of borderline personality disorder on the SCID II, for severity of childhood maltreatment on interview and self-report measures, and for disturbance in parent-child interaction during a videotaped conflict discussion task. Borderline traits, as well as suicidality/self-injury specifically, were associated with more role confusion and more disoriented behavior in interaction with the parent. Among young adults with recurrent suicidality/self-injury, 40% displayed high levels of role confusion compared to 16% of those who were not suicidal. Neither form of disturbed interaction mediated the independent effect of childhood abuse on borderline symptoms. A parent-child transactional model is proposed to account for the findings.