To study the role of catastrophic interpersonal cognitions in panic disorder with or without agoraphobia, a questionnaire listing such items – the Interpersonal Panic Fear Questionnaire (IPFQ) – was constructed and administered to English and Norwegian samples. The results of the factor analysis indicated a three-factor structure of interpersonal fears: fear of negative evaluation, fear of being trapped and separated from safe persons and places, and fear of being neglected. The corresponding three IPFQ scales had satisfactory internal consistency and sensitivity to change following therapeutic intervention, discriminated well between diagnostic groups, and correlated moderately with measures of other dimensions of panic disorder and agoraphobia. The construct validity of the interpersonal fears was further supported by mostly significant relationships between the IPFQ scales and a measure of agoraphobic avoidance, when the contribution of intrapersonal (physical, loss of control) fears was controlled.