Chronic pain and post-traumatic stress disorder (PTSD) are frequently observed within the Department of Veterans Affairs healthcare system and are often associated with a significant level of affective distress and physical disability. Clinical practice and research suggest that these two conditions co-occur at a high rate and may interact in such a way as to negatively impact the course of either disorder; however, relatively little research has been conducted in this area. This review summarizes the current literature pertaining to the prevalence and development of chronic pain and PTSD. Research describing the comorbidity of both conditions is reviewed, and several theoretical models are presented to explain the mechanisms by which these two disorders may be maintained. Future directions for research and clinical implications are discussed.