This paper reviews the theoretical, conceptual and empirical literature relating to emotional regulation in borderline personality disorder. A number of issues relating to the disorder are discussed, including problems with the categorical system of diagnosis and potential co-morbidity. The prominent models of treatment are reviewed along with the evidence for their effectiveness. The concept of a core dysregulation of emotion in the disorder is considered and the psychological models of emotion explored. A systematic review is then described that identified twenty-one experimental studies that investigated aspects of emotional dysregulation in the disorder. The results of this review are categorised into subgroups on the basis of the experimental methods used, and discussed within this context. The results provide limited support for the concept of emotional sensitivity, with empirical evidence for increased attention to emotional stimuli but no evidence of a lower threshold of emotional response. Increased emotional intensity has been demonstrated with self-report and time-sampling data, however results from physiological measures are inconsistent. The limitations of the current literature are discussed, and the implications for future research and clinical practice are considered.