An 8-item version of the Chronic Pain Acceptance Questionnaire (CPAQ-8) has recently been proposed and validated. The aims of this study were to further investigate the reliability and validity of the CPAQ-8 in a new sample. Questionnaires were completed by 550 people with chronic pain (478 online survey, 72 paper survey). A demographic and pain history questionnaire was administered along with the CPAQ-8 and measures of pain self-efficacy, pain catastrophizing, psychological flexibility in pain, anxiety, and mood. In addition, 105 respondents completed the CPAQ-8 within 6 weeks to provide test-retest reliability data. The 2-factor structure of the CPAQ-8 (Activity Engagement [AE] and Pain Willingness [PW]) was confirmed and had reasonable-to-good scale score reliability and test-retest reliability. Pain acceptance as measured by the CPAQ-8 was associated with less depression, anxiety, pain interference, fear of reinjury, pain catastrophizing, and psychological inflexibility in pain, and higher levels of satisfaction with life, pain self-efficacy, and general acceptance. Furthermore, pain acceptance fully mediated the relationship between reported pain severity and emotional distress (anxiety and depression) and partially mediated the relationship between pain severity and pain interference in a structural equation model. The test-retest reliability after 4 to 6 weeks ranged from .68 for PW to .86 for AE; the overall score correlation was .81. We conclude that the CPAQ-8 is a reliable and valid measure of pain acceptance and that the 2 subscales of the measure each make an individual contribution to the prediction of adjustment in people with chronic pain.The present study provides further evidence for the reliability and validity of the CPAQ-8. Support was found for the 2 related subscales, PW and AE, which appear to work in synergy to influence levels of pain interference and emotional distress in people living with chronic pain.