The Diagnostic and Statistical Manual for Mental Disorders-5th Edition (DSM-5; American Psychiatric Association [APA], 2013) includes an alternate model for the assessment and diagnosis of personality disorders (PDs). This model is a hybrid dimensional-categorical model that includes functional impairment, maladaptive personality traits, and a set of categorical PD diagnoses. Previous research has begun to evaluate the different aspects of this model, particularly its trait model (see Krueger & Markon, 2014 for a review); however, additional research is needed that addresses the clinical utility of the model, the role of functional impairment in PD assessment, and validity of measure designed to assess the model (e.g., the Personality Inventory for DSM-5 [PID-5] and its alternate forms). The following studies aimed to fill those gaps in the literature. Study One evaluated clinical perspectives of Borderline (BPD) and Antisocial (ASPD) PDs using Section III dimensional traits and supported the use of these traits in operationalizing these two disorders in clinical practice. Study Two examined the functional impairment criteria of the model as they relate to specific PDs. This study suggested a lack of utility in measuring disorder-specific impairment due to overlap across PDs and instead suggested the use of more broad constructs of impairment. In addition, however, this study highlighted some of the overlap between functional impairment and maladaptive traits in this model, as described by other previous researchers (e.g., Zimmerman et al., 2015) and called for additional research regarding the utility of this criterion. Finally, Study Three evaluated a screening measure for the Section III trait domains, the PID-5-Brief Form (PID-5-BF; APA, 2013; Derringer et al., under review). This study found support for the factor structure of this measure as well as its construct validity as measured by its association with relevant external criterion variables. Although more research continues to be needed regarding the use of this alternative model, these studies have implications for its implementation and generally support the use of dimensional traits in the assessment and diagnosis of personality psychopathology.