The extensive comorbidity among Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]; American Psychiatric Association, 1994) personality disorders might be compelling evidence of essential commonalities among these disorders reflective of a general level of personality functioning that in itself is highly relevant to clinical decision making. This study sought to identify key markers of such a level, thought to reflect a core dimension of personality pathology involving impairments in the capacities of self and interpersonal functioning, and to empirically articulate a continuum of severity of these problems for DSM-5. Using measures of hypothesized core dimensions of personality pathology, a description of a continuum of severity of personality pathology was developed. Potential markers at various levels of severity of personality pathology were identified using item response theory (IRT) in 2 samples of psychiatric patients. IRT-based estimates of participants' standings on a latent dimension of personality pathology were significantly related to the diagnosis of DSM-IV personality disorder, as well as to personality disorder comorbidity. Further analyses indicated that this continuum could be used to capture the distribution of pathology severity across the range of DSM-IV personality disorders. The identification of a continuum of personality pathology consisting of impairments in self and interpersonal functioning provides an empirical foundation for a levels of personality functioning rating proposed as part of a DSM-5 personality disorder diagnostic formulation.