AbstractAimNo measure has formally been developed to assess the published ICD‐11 model of Personality Disorder (PD) severity. We therefore set out to develop and evaluate the 14‐item Personality Disorder Severity ICD‐11 (PDS‐ICD‐11) scale.MethodA representative U.S. community sample (N = 428; 50.9% women) and a New Zealand mental health sample (N = 87; 61.5% women) completed the PDS‐ICD‐11 scale along with a series of established PD and impairment measures.ResultsItem response theory supported the unidimensionality of PDS‐ICD‐11 (median item loading of 0.68) and indicated that a PDS‐ICD‐11 score of 17.5 may serve as a benchmark for pronounced dysfunction. Correlation and regression analyses supported both criterion validity and incremental validity in predicting impairment and PD symptoms. The PDS‐ICD‐11 was particularly associated with measures of Level of Personality Functioning Scale (LPFS), Global PD severity, and Borderline PD symptom score. A comparison between clinical individuals diagnosed with an ICD‐11 PD vs. no PD supported diagnostic validity.ConclusionThis initial construction study suggests that the PDS‐ICD‐11 constitutes a promising instrument that provides a quick impression of the severity of personality dysfunction according to the official ICD‐11 PD guidelines. Clearly, more research is needed to corroborate its validity and utility. The PDS‐ICD‐11 scale is provided as online supporting information.