The present study investigated the relationship between baseline levels of affect integration and the magnitude of change during and after open-ended psychotherapy. Affect integration reflects the capacity for accessing and utilizing the adaptive properties of affects for personal adjustment, along with the more general capability of tolerating and regulating affective activation. It is thus a capacity with relevance for the postulated mechanisms of change in various treatment modalities. Overall, the results indicated that patients with more severe problems in affect integration had larger improvements in symptoms, interpersonal and personality problems in open-ended treatment than those with less severe problems. This was also the case when examining the predictive effects of the integration of specific affects on changes in interpersonal relatedness. It was indicated that increasing problems with the integration of discrete affects were associated with distinct patterns of change in different interpersonal problem domains.