The authors tested whether borderline personality disorder (BPD) is characterized by interpretation bias for disambiguating stimuli in favor of threatening interpretations, especially concerning abuse, abandonment, rejection, and anger-core emotional triggers for BPD patients. A mixed sample of 106 patients with marked BPD traits and nonpatients were assessed with SCID I and II and were presented with vignettes depicting ambiguous social interactions. Interpretations of these vignettes were assessed both in a closed and an open answer format. Results showed that BPD traits were related to a rejection- (closed and open answer formats) and an anger-related interpretation bias (closed answer option only). Cluster C traits were associated with self-blame interpretations. Aside from further validating the cognitive model of BPD, these findings denote interpretation bias as a key feature in patients with BPD that might contribute to their emotional hyperreactivity and interpersonal problems. These findings also highlight the importance of therapeutically normalizing interpretative bias in BPD and cluster C patients.