Personality characteristics and disorders have long been noted in the chronic pain population. Clinicians and researchers alike will attest to the high rates of personality difficulties encountered in these individuals. Historically, it has been found that certain personality styles such as hypochondriasis and hysteria are common in chronic pain suffers. In addition, the prevalence of personality disorders (PDs) is significantly greater in the pain population than in the general population or in medical or psychiatric populations. A diathesis-stress model has been suggested to account for this finding and is discussed in this article, with implications for both treatment and research.