It has long been recognized that there is a relationship between certain personality types and personality disorders (PD) and chronic nonmalignant pain (CP). The relationship, however, is far from understood and the physiological and psychological mechanisms that underlie it are unclear. Those who treat chronic pain face many challenges when dealing with individuals who have personality disorders and they often become frustrated when interacting with these patients. Patients with certain traits and personality disorders may continue to worry and ruminate about their symptoms long after the tissue pathology has resolved. Other individuals may overly rely on the clinician and assume a passive role in their treatment, thereby decreasing the likelihood for a positive outcome. Moreover, patients with personality disorders may be demanding (eg, borderline), self-absorbed (eg, narcissistic), or substance seeking (eg, antisocial, borderline). In an attempt to improve management of such patients, pain specialists have attempted to better understand the complex relationship between personality and chronic pain. In this article, we will review the predominant historical and current theories of pain and personality, discuss aspects of the gate-control theory of pain that may relate to personality, and discuss the diathesis-stress model of personality disorders in pain. Last, we will review studies of personality and personality disorders in chronic pain and their treatment implications. We conclude that, based on the underlying neurochemistry, there may be a direct or indirect link between PD and CP, but further prospective research, both on the biological and psychological relationship, should be conducted.