Despite the widespread use of methods that are supposed to detect the sincerity of patients' efforts in clinical assessment, little has been written summarizing the literature that addresses the reliability and validity of measurements obtained with these methods. The purpose of this article is to review the literature on the reliability and validity of scores for Waddell's nonorganic signs, descriptions of pain behavior and symptom magnification, coefficients of variation, correlations between musculoskeletal evaluation and function, grip measurements, and the relationship between heart rate and pain intensity. The authors of the articles reviewed conclude that none of these methods have been examined adequately. Some of these methods, such as Waddell's nonorganic signs, were not developed for the purpose of detecting sincerity of effort. Clinicians are encouraged to critically read the literature addressing these methods. With further research, some of the discussed methods may prove useful. Until such research is reported in the peer-reviewed literature, however, clinicians should avoid basing evaluation of sincerity of effort on these tests. Therapists are encouraged, instead, to use a biobehavioral approach to better understand and address the complex factors underlying delayed recovery.