The International Classification of Diseases, 11th Edition (ICD-11) has reconceptualized personality disorders (PD), and measures are therefore being developed to aid the assessment of ICD-11 PD. The present study examined the validity of the recently developed self-report inventory the Personality Disorder Severity for ICD-11 (PDS-ICD-11), and its utility in differentiating across ICD-11 PD severity levels in a community mental health sample (n = 232). We examined the associations between the PDS-ICD-11 with various clinician ratings, self-report questionnaires, and informant-report measures of dimensional personality impairment and traditional Diagnostic and Statistical Manual of Mental Disorders, fifth edition PDs. Further, we examined mean group differences in PDS-ICD-11 scores between levels of ICD-11 PD clinician diagnosis. The PDS-ICD-11 exhibited moderate-to-large associations with all clinician ratings, and more variable associations with self-report and informant-report measures. PDS-ICD-11 mean scores were significantly different across all levels of ICD-11 PD clinician-rated diagnostic levels. These findings provide additional promising evidence for the validity and utility of the PDS-ICD-11 for the assessment of ICD-11 PD in community mental health patients. Public Significance Statement ICD-11 personality disorder is a new diagnosis, which requires valid assessment measures. The PDS-ICD-11 is an efficacious brief screening tool for researchers and clinicians interested in ICD-11 personality disorder. The present study provides support for validity and utility of this new measure.