With the dimensional shift, personality pathology is now commonly conceptualized using a combination of personality functioning and (pathological) personality traits. Personality functioning has been deemed more sensitive to treatment than the specific trait combination of personality problems. To empirically examine just that, the goal of this pilot study was to simultaneously compare changes in personality functioning (LPFS-BF 2.0), pathological traits (PID-5-BF), and normal-range traits (BFI-2) among individuals receiving integrative, dynamic-relational psychotherapy (baseline n = 52, follow-up n = 31) and a matched control group (n = 31). The results showed that clients had stronger changes in personality functioning than in traits when compared to the control group. In addition, clients lower on personality functioning were more inclined to drop-out of therapy. This study points to the unique clinical utility of personality functioning and provides a foundation for future research focusing on the sensitivity of personality functioning and personality traits to changes within the context of psychotherapy.