Proposed for the ICD-11 is a dimensional model of personality disorder that, if approved, would be a paradigm shift in the conceptualization of personality disorder. The proposal consists of a general severity rating, 5 maladaptive personality trait domains, and a borderline pattern qualifier. The general severity rating can be assessed by the Standardized Assessment of Severity of Personality Disorder (SASPD), the trait domains by the Personality Inventory for ICD-11 (PiCD), and the borderline pattern by the Borderline Pattern Scale (BPS), which is developed in the present study. To date, no study has examined the relations among all 3 components, due in part to the absence of direct measures for each component (until recently). The current study develops and provides initial validation evidence for the BPS, and examines the relations among the BPS, SASPD, and PiCD. Also considered is their relationship with the 5-factor model of general personality as well as with 2 other measures of personality disorder severity (including the DSM-5 Level of Personality Functioning Scale [LPFS]). Further, an alternative trait-based coding of the DSM-5 LPFS is examined (modeled after the ICD-11 SASPD), suggesting that its coverage of diverse maladaptivity may not be because it assesses the core of personality disorder, but rather because it has items specific to the different domains of personality. (PsycINFO Database Record (c) 2019 APA, all rights reserved).