Cluster B personality disorders (PDs) share specific traits that can result in interpersonal conflict. As therapeutic working alliance has a strong relationship with improved outcomes, there is interest in understanding the relationship between PDs, working alliance, and clinical outcomes. This is especially compelling in inpatient populations, where symptoms are severe, and patients are working with a treatment team. The aims of this study were to (a) assess whether higher team working alliance is associated with lower depressive symptoms, (b) assess whether patients with Cluster B PD traits have worse working alliance with their team than patients without those Cluster B PD traits, and (c) assess whether higher team working alliance is associated with lower depressive symptoms when Cluster B PD traits are present. Team working alliance was measured at baseline and at discharge for 3,406 inpatients at a psychiatric hospital. Improved team working alliance was associated with lower depression scores at discharge. Patients with borderline personality disorder traits had worse team working alliance, whereas patients with narcissistic personality disorder and antisocial personality disorder traits had similar working alliance scores as other patients. Borderline personality disorder and antisocial personality disorder traits moderated the association between team working alliance and depressive symptoms differently. Findings suggest that team working alliance works similarly to therapist working alliance. Of clinical importance is the finding that team working alliance and its relationship with depression symptoms differ based on Cluster B PD traits, and the importance of strong working alliance regardless of interpersonal challenges due to personality pathology. (PsycInfo Database Record (c) 2023 APA, all rights reserved).