This study investigated the role of both negative and positive cognitions in predicting panic severity in an international sample of patients diagnosed with panic disorder (with and without agoraphobia). One hundred and fifty-nine patients were administered the Brief Bodily Sensations Interpretation Questionnaire (BBSIQ), the Self-efficacy to Control Panic Attacks Questionnaire, and the Panic and Agoraphobia Scale (PAS) prior to receiving treatment. Regression analyses indicated that both catastrophic misinterpretation of bodily sensations and panic self-efficacy independently predicted panic severity. The influence of panic self-efficacy upon panic severity remained significant even after controlling for the presence or absence of agoraphobia. There was no evidence to suggest a moderating relationship between the two cognitive factors. Results are discussed in terms of the need to consider both negative and positive cognitions in cognitive accounts of panic disorder.