Professor Bernard Granger is a psychiatrist and psychotherapist and a member of the French Association for Cognitive and Behavioural Therapies. He teaches at Paris-Descartes University and heads the Psychiatric Unit at Tarnier Hospital. Daria Karaklic is a doctor in clinical psychology and a teaching and research fellow in psychopathology at the Institute of Psychology at Paris-Descartes University. What exactly is a borderline personality disorder? First defined at the end of the nineteenth century, the disorder has become widespread during the past decade. But is it an actual pathology - or could the label "borderline" simply be a useful catchall term? About 2% of the population suffers from BPD, a disorder characterised by mood swings, intense emotions, excessive reactions to the emotions of others, anxiety, anger, alterations in perception and reasoning, feelings of emptiness, self-mutilation, attempted suicide, etc. The authors provide a thorough description of the borderline personality and its symptoms. The authors attempt to shed light on the causes of BPD and, particularly, to show that'solutions exist, thanks to psychotherapy and the support of medication.- Borderline personality disorder can be overcome - but information is crucial.- The authors provide a wealth of precise, up-to-date information.