The predominant maladaptive trait models are now provided by Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5) Section III, assessed by the Personality Inventory for DSM-5 (PID-5; Krueger, Derringer, Markon, Watson, & Skodol, 2012), and the International Classification of Diseases-11th Revision (ICD-11; assessed by the Personality Inventory for ICD-11 (PiCD; Oltmanns & Widiger, 2018). However, 2 historical precedents are the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ; Livesley & Jackson, 2009) and the Schedule for Nonadaptive and Adaptive Personality (SNAP; Clark, 1993). The current study administered the DAPP-BQ, SNAP, PiCD, and PID-5 to a sample of 323 persons with a history of mental health treatment. The results provided support for the historical precedence of the DAPP-BQ and SNAP, although also suggest that additional traits should perhaps be included in current models. The results also bear on additional ongoing issues, including (but not limited to) the bipolarity of maladaptive personality structure, the conceptualization of identity problems as a trait, and the discriminant validity of maladaptive trait models and their assessment. (PsycINFO Database Record (c) 2019 APA, all rights reserved).