Many authors report that a high percentage of patients with chronic pain have no or insufficient underlying physical pathology to explain their pain. Even when patients do have an identified diagnosis, many patients profess to have little understanding of the source of their pain or fear that they may suffer from more severe pathology. This may be particularly true for patients with chronic musculoskeletal pain given the lack of “objective” findings for soft tissue pain complaints. In the present study, we examined whether chronic neck and back pain patients were able to identify the physiologic source of their pain, and based on their responses patients were placed in one of three groups: (1) patients who did not know the cause of their pain; (2) patients who did know the cause and agreed with their clinical diagnosis; and (3) patients who identified a cause for their pain that was different from their clinical diagnosis. The sample was comprised primarily of individuals with musculoskeletal pain problems (70%) referred to an outpatient chronic pain rehabilitation program. Each patient completed a pretreatment test battery, and group differences were examined on responses to the McGill Pain Questionnaire, Survey of Pain Attitudes, Brief Symptom Inventory, Coping Strategies Questionnaire, and Pain Disability Index. Upon initial evaluation, 47.2% n=85) of patients indicated that they did not know what was causing their pain. Of patients who articulated a cause for their pain, 20% (n=36) attributed it to factors that did not agree with their diagnosis. Only 32.8% (n=59) of persons in the entire sample were able to accurately identify the cause of their pain. Patients who disagreed with their clinical diagnosis were more likely to be diagnosed with musculoskeletal pain and reported the highest levels of pain (F(2,169)=3.41, p <.05) as well as the greatest levels of affective distress (F(2,169)=3.54, p < .05). Patients who were unsure of or disagreed with their diagnosis tended to report a greater belief in pain being a signal of harm (F(2,169)=11.5,p <.001) and described themselves as more disabled (F(2,169)=8.43, p < .001). In addition, both the “unsure” and “disagree” groups tended to use maladaptive pain strategies more frequently, and persons unsure of their diagnosis had the lowest levels of perceived control over pain. A hierarchical regression analysis examining a cognitive/behavioral model of pain disability indicated that lack of knowledge of pain etiology, a belief that pain is a signal of harm, catastrophizing and affective distress all significantly predicted increased disability, while pain intensity did not. The data suggests that lack of knowledge about the origin of pain is associated with maladaptive cognitions in relation to pain (i.e., fear of harming oneself and catastrophizing) and increased emotional distress which in turn are related to heightened disability due to pain. These data argue that educating patients regarding their diagnosis and the origin of their pain, thereby dispelling dysfunctional pain beliefs, may be an important component of pain treatment, particularly among patients with chronic musculoskeletal pain.