Intersession process in psychotherapy refers to the thoughts, memories, and feelings about each other and about their therapy sessions that participants experience during the intervals between sessions. This study compared the intersession process experienced by patients who had been diagnosed with severe borderline personality disorders (BPD) with others who had not. A total of 76 patients with neurotic disturbances and 20 patients with BPD were treated in a therapeutic day clinic and completed the Intersession Experience Questionnaire (IEQ) before sessions of individual psychotherapy and the Session Questionnaire (Stundenbogen) after those sessions. Comparison of the two groups on these measures of intersession process and postsession outcome showed markedly different patterns in patients' evaluations and internalizations of in-session therapeutic experiences: most prominently, that BPD patients internalize therapy sessions with much more negative and contradictory emotions.