One of the most difficult aspects of performing independent medical examinations (IME) is the assessment of individuals with pain complaints (eg, neck or low back pain) for which no clear and objective basis can be determined. This two-part article critiques chronic pain models and presents a useful construct based on well-validated psychiatric diagnoses. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) attempts to evaluate pain in the context of the underlying, objectively defined impairment and considers pain to be of secondary importance. Physicians differ sharply concerning the contributions of neurophysiological vs behavioral/psychological factors when pain is present without general medical findings (eg, fibromyalgia). Chronic pain syndrome diagnosed by the “Eight Ds in Chronic Pain” is superficially attractive but seriously inadequate. Evaluators are challenged by poorly validated criteria for certain diagnoses and questions about the accuracy of patient self-reports. The AMA Guides, Sixth Edition, does not use range of motion to determine spinal impairment, and in most cases electrodiagnosis has little to add. Impairment and disability assessment of individuals with pain complaints is one of the greatest challenges encountered by IMEs, and future challenges will involve taking into account both the subjective factors and the difficulties inherent in evaluating another person's subjective experiences.