The DSM–5 Section III alternative model for personality disorders (AMPD) distinguishes general personality impairment from trait-based descriptions of personality disorder expression. The inclusion of the AMPD in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM–5) provides a scaffold for classification and diagnosis of personality pathology that merits further efforts to improve upon its assessment framework. Recent empirical work focuses on evaluating the reliability and validity of the Level of Personality Functioning Scale and the Personality Inventory for the DSM–5, demonstrating the structural and predictive distinctiveness of measures of pathological personality traits and impairment, evaluating practitioner acceptance and clinical utility, and examining associations with other important outcomes. To complement the increased research on the AMPD, this article focuses on the relevance of distinguishing levels of personality functioning and pathological personality traits in clinical practice. We present three cases of patients exhibiting pathological narcissism that vary in terms of severity of general personality dysfunction and prominent pathological personality traits assessed through the DSM–5 AMPD. We demonstrate that the DSM–5 AMPD provides the clinician with diagnostic criteria that exhibit greater fidelity with the varied presentations of pathological narcissism seen in clinical practice. We conclude that the DSM–5 AMPD provides a useful framework for incorporating different clinical presentations of narcissistic grandiosity, as well as characteristics of narcissistic vulnerability into the diagnosis of narcissistic personality disorder. Finally, we suggest that the clinical relevance of pathological traits in psychotherapy differs as a function of severity of personality impairment.