The purpose of this study was to examine the relationships among negative affect, childhood sexual abuse (CSA), thought suppression, and diagnostic symptoms of borderline personality disorder (BPD) in a community sample (n=127). Findings suggest that the temperamental variable negative affect intensity/reactivity was a stronger predictor of BPD symptoms than CSA. In addition, results indicated that higher thought suppression mediated the relationship between negative affective intensity/reactivity and BPD symptoms, after controlling for a history of CSA. Overall, findings suggest that (a) negative affectivity may be a better predictor of BPD symptoms than CSA, and (b) chronic efforts to suppress unpleasant thoughts may be a regulation strategy underlying the relationship between intense negative emotions and BPD symptoms.