It is important to understand the change processes involved in psychotherapies for patients with personality disorders (PDs). One patient process that promises to be useful in relation to the outcome of psychotherapy is emotional processing. In the present process-outcome analysis, we examine this question by using a sequential model of emotional processing and by additionally taking into account a therapist's appropriate responsiveness to a patient's presentation in clarification-oriented psychotherapy (COP), a humanistic-experiential form of therapy. The present study involved 39 patients with a range of PDs undergoing COP. Session 25 was assessed as part of the working phase of each therapy by external raters in terms of emotional processing using the Classification of Affective-Meaning States (CAMS) and in terms of the overall quality of therapist-patient interaction using the Process-Content-Relationship Scale (BIBS). Treatment outcome was assessed pre- and post-therapy using the Global Severity Index (GSI) of the SCL-90-R and the BDI. Results indicate that the good outcome cases showed more self-compassion, more rejecting anger, and a higher quality of therapist-patient interaction compared to poorer outcome cases. For good outcome cases, emotional processing predicted 18% of symptom change at the end of treatment, which was not found for poor outcome cases. These results are discussed within the framework of an integrative understanding of emotional processing as an underlying mechanism of change in COP, and perhaps in other effective therapy approaches for PDs.