The relative efficacy of cognitive restructuring and interoceptive exposureprocedures for the treatment of panic disorder, as well as the differentialeffects of the order of these interventions, was studied. Eighteen clientswith panic disorder were seen for four sessions of exposure therapy and foursessions of cognitive therapy in a crossover design study. Half of theparticipants received exposure therapy followed by cognitive therapy and forhalf the order was reversed. There was a 1-month follow-up period between the two interventions and after the second intervention. Questionnairemeasures and independent clinician ratings were used to assessoutcome. Participants expected greater benefit from cognitive therapy, buttended to improve to a similar degree with either intervention. The order inwhich treatments were presented did not influence outcome. Participantstended to improve with the first intervention and maintain improvementacross the follow-up periods and subsequent intervention. Severalmethodological limitations qualify the conclusions that can be drawn fromthis study. These limitations, as well as some conceptual and methodologicalchallenges of conducting this type of research, are discussed.