Over the past decade, there has been a burgeoning of interest in understanding and treating borderline personality disorder, a disorder characterized by extreme emotional reactivity, impulsivity and serious interpersonal difficulties resulting in frequent loss of relationships. Individuals with borderline personality disorder comprise a substantial proportion of the psychiatric outpatient population, are often seen in emergency rooms and have major functional impairment (e.g. unemployment). Suicide occurs in 3-9% of the population. Furthermore, non-suicidal self injury (e.g. cutting without the intent to die), eating disorders and substance abuse are frequently seen in the context of borderline personality disorder. Not only do the individuals with the disorder suffer , their family members also experience distress and can feel burdened and overwhelmed. Once thought to be nonexistent or a ''grab bag'' diagnosis, borderline personality disorder is now understood as a significant emotional disorder with its own neurobiological and psychosocial correlates. At the same time, the disorder is still poorly understood and stigmatized with limited resources available to the novice clinician and mental health professional trainees (e.g. psychiatry residents, psychology doctoral students, social work students). The aim of this primer on borderline personality disorder is to fill this void and provide an accessible, easy-to-use , clinically-oriented, evidenced-based guide for early stage clinicians. We present the most up to data about borderline personality disorder by leading experts in the field in a format accessible to trainees and professionals working with individuals with borderline personality disorder and their family members. The volume is comprehensive and covers the etiology of BPD, its clinical presentation and co-morbid disorders, genetics and neurobiology of BPD, effective treatment of BPD, the role of advocacy and special subpopulations (e.g.forensic)in the clinical management of BPD.