This paper reports upon: (1) the value of acceptance of pain in predicting well-being in patients suffering from chronic pain and (2) the construct validity of acceptance by comparing two questionnaires designed to measure acceptance (the Chronic Pain Acceptance Questionnaire, CPAQ, unpublished doctoral dissertation, University of Nevada, Reno, NV, 1992 and the Illness Cognitions Questionnaire, ICQ, J Consult Clin Psychol 69 (2001) 1026). The results of two independent cross-sectional studies are reported. Study 1 included 120 patients seeking help in tertiary care settings. In Study 2, 66 patients were recruited from a self-support group for fibromyalgia patients and from a pain clinic. Both studies revealed that acceptance of pain predicted mental well-being beyond pain severity and pain catastrophizing, but did not account for physical functioning. In both instruments, it was found that acceptance of pain was strongly related to engagement in normal life activities and the recognition that pain may not change. Acceptance in both instruments was strongly related to a cognitive control over pain. Study 2 further revealed that the correlation between the CPAQ and the ICQ is moderate, indicating that both instruments measured different aspects of acceptance. It is concluded that acceptance of chronic pain is best conceived of as the shift away from pain to non-pain aspects of life, and the shift away from a search for a cure with an acknowledgement that pain may not change.