Borderline personality disorder (BPD) is an Axis II disorder that is characterized by an intact façade, longstanding self-regulation difficulties and self-harm behavior, and unstable interpersonal relationships and mood. According to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV; American Psychiatric Association, 1994), the prevalence of BPD in the general population is around 2%. The symptoms of the disorder appear to be influenced by gender. Despite defined diagnostic criteria, BPD tends to have polymorphic clinical presentations with both multiple psychological and somatic symptoms. The etiology of BPD appears to be related to genetic predisposition, early developmental trauma, and biparental failure, although other contributory factors may be involved. We discuss, through the use of several models, the possible relationships between BPD and eating disorders.