Personality disorders (PDs) are among the most common and severe classes of psychopathology. From a clinical perspective, it is challenging to help individuals with personality disorders because treatment ruptures, discontinuation, reversals, and failures are relatively common. An additional clinical challenge is that the model used to diagnose personality disorders is demonstrably incorrect. Recent efforts to improve diagnosis of personality disorders apply two criteria: the first distinguishes personality disorders from other kinds of psychopathology and the second distinguishes different types of personality disorders. However, this approach has been problematic in that, as currently operationalized, it does not provide a clear demarcation for personality disorders, and it uses a framework for individual differences that is more apt as a model of variation in psychopathology in general. This article proposes that the core of personality disorders involves difficulties understanding and relating to self and others, and thus the personality disorders should be recast as the interpersonal disorders. Interpersonal dysfunction explains extreme social challenges and treatment difficulties that are characteristic of this class of psychopathology. This approach provides a clearer model for distinguishing these kinds of problems, as demonstrated by reformulating traditional personality disorder symptoms from an interpersonal perspective. (PsycInfo Database Record (c) 2023 APA, all rights reserved).