The Chronic Pain Acceptance Questionnaire (CPAQ) is a measure of pain acceptance comprised of pain willingness (PW) and activity engagement (AE; McCracken et al., 2004). Concerns about the factorial structure of the CPAQ exist, as it is not yet clear whether PW and AE constitute 2 independent constructs or 1, pain acceptance. Concerns also exist about the internal and predictive validity of test score interpretations of this measure. This study also presents that the choice of predictor variables has contributed to theoretical confusion regarding the impact of pain acceptance on pain-related adjustment. The purpose of this study was: (a) to examine the psychometric properties of both the long (20 items) and short (8 items) versions of the Greek-Chronic Pain Acceptance Questionnaire (G-CPAQ); (b) to examine the utility of a 2-factor solution in predicting psychosocial adjustment to pain using confirmatory factor analysis; and (c) to explore the mediating effects of pain acceptance and cognitive defusion, comprising the “open” response style to pain, between pain interference and pain related outcomes. One hundred and sixty chronic pain patients completed a questionnaire packet including pain indexes, pain acceptance, cognitive fusion, avoidance, and emotional distress. Confirmatory factor analyses supported the 2-factor solution, though a general good model fit was achieved only for the short G-CPAQ version. Structural equation modeling showed that PW and AE coupled with cognitive defusion partially mediated the influence of pain interference on pain severity, emotional distress, and avoidance of pain.