While some people use active coping strategies and are able to adaptively cope with their pain, others use passive strategies and catastrophic appraisals, which are often associated with increased displays of pain behavior and negative pain-related outcomes. To investigate attribution-based implicit theories as a potential underlying mechanism that might affect coping success, it is hypothesized that pain patients with an incremental implicit theory of pain (i.e., view pain as malleable) would have more active coping strategies, lower levels of pain expressiveness, and better pain-related outcomes than those with an entity implicit theory of pain (i.e., view pain as nonmalleable). Patients with chronic back pain undergoing a functional assessment completed a variety of self-report measures and participated in a pain-inducing physiotherapy procedure. The results showed those with an incremental theory of pain used more active coping strategies, displayed less pain behavior, and reported better pain-related outcomes (e.g., lower levels of depression) than individuals with an entity theory of pain. The findings indicate implicit theories of pain may represent an underlying social-cognitive mechanism linked to important coping, emotional, and expressive reactions to chronic pain. Identifying such a mechanism might produce valuable information for the assessment and treatment of chronic pain.