Although borderline personality disorder (BPD) is a major public health concern, psychotherapeutic trials have been limited. The present uncontrolled clinical trial examines whether cognitive therapy for BPD is associated with significant improvement on measures of psychopathology. A total of 32 patients with BPD, who also reported suicide ideation or who engaged in self-injury behavior, received weekly cognitive therapy sessions over a 1-year period as described by Layden et al. (1993). The results revealed significant and clinically important decreases on measures of suicide ideation, hopelessness, depression, number of borderline symptoms and dysfunctional beliefs at termination and 18-month assessment interviews. Implications for further research with this difficult-to-treat patient population are discussed.