In the past fifty years psychological factors have been shown to influence adjustment to chronic pain. Research demonstrates that individuals’ internal representations of pain and the processes of catastrophising (focusing on negative outcomes) and acceptance (acknowledging pain but continuing to live a fulfilling life) are important. The aim of the present study is to examine how the processes of catastrophising and acceptance interact with illness representations to influence physical and emotional functioning. The psychological and functioning variables were assessed using validated questionnaires completed by individuals attending NHS Pain Clinics and pain support groups in the community. Path analyses were conducted to investigate whether catastrophising or acceptance mediated relationships between illness representations and emotional and physical functioning. Catastrophising mediated the relationship between other psychological factors (representations of control, emotional responses to pain, acceptance) and emotional functioning. Acceptance mediated the relationship between other psychological factors (perceptions of consequences, catastrophising)and physical functioning. The findings suggest that different psychological processes may underlie successful emotional and physical functioning in chronic pain. The clinical and theoretical implications of the results are discussed, as are directions for future research including the need for the development of experimental designs and intervention studies. This research would help clarify the causal status of catastrophising and acceptance in chronic pain and thereby advance psychological theory about successful functioning.