Proponents of the use of cotherapists have stressed the importance of compatibility for effective cotherapy teams; however, the nature of compatibility has received little attention in experimental literature. This study investigated the nature of an effective cotherapy relationship through use of concepts espoused by George Kelly in his personal construct theory. Based on the results of the study, it was recommended that cotherapists be paired on the basis of their cognitive congruence. It was further proposed that cotherapists, especially those low in content congruence, allow themselves sufficient time for case discussion prior to and following their therapy sessions.