Background: Cognitive- and acceptance-based approaches are used to help people live with chronic pain. Little is known about how these constructs relate to each other. In this study, we examined how cognitive representations of chronic pain relate to interpersonal styles such as catastrophizing and the behavioural process of acceptance of chronic pain. This study further examined how these processes relate to emotional and physical functioning in chronic pain. Methods: A cross-sectional design, employing validated questionnaires, was used to measure pain, emotional and physical dysfunction, illness representations, catastrophizing and acceptance in a heterogeneous sample of 150 chronic pain sufferers. Results: The psychological variables significantly mediated the impact of pain severity on both emotional and physical dysfunction. In addition, a distinct pattern of mediation was observed. The relationship between pain and emotional dysfunction was mediated by representations of pain as a highly emotive experience and by catastrophizing; acceptance did not mediate this relationship. By contrast, the relationship between pain and physical dysfunction was mediated by acceptance and representations of high consequences of chronic pain, but not by catastrophizing. Conclusions: Pain severity itself is a relatively poor predictor of emotional and physical dysfunction in chronic pain states. These relationships are significantly mediated by psychological variables. Different approaches to chronic pain rehabilitation emphasize different targets (changing illness representations and reducing catastrophizing vs. acceptance and behavioural activation). This cross-sectional study suggests that these processes may differentially influence outcomes, but that they are complex and overlapping. Theoretical and clinical implications are discussed.