Previous research has demonstrated that maladaptive cognitive content, including dysfunctional attitudes and negative automatic thoughts, is associated with emotional distress. Similarly, dysfunctional cognitive processes, including thought suppression and rumination, have been shown to intensify psychological difficulties. Although maladaptive cognitive content and dysfunctional processes have been linked to borderline personality disorder (BPD), most research has been conducted with Axis I disorders. This study examined the incremental validity of dysfunctional cognitive content and processes in predicting BPD symptom severity, controlling for trait negative affect, in a sample of undergraduate students (N = 85), including many with high levels of BPD features. Although nearly all variables were significantly correlated with BPD features, final regression models suggest that rumination and thought suppression are stronger independent predictors of BPD features than automatic thoughts, dysfunctional attitudes, and trait negative affect. These results suggest the importance of targeting thought suppression and rumination in BPD.