ABSTRACT
Personality functioning (PF) is the defining criterion for personality disorder in contemporary diagnosis and a popular topic in research. However, research and dialogue on PF has been uneven and often ideologically driven, in part because semantic differences are often conflated with substantive differences in the way PF is conceptualized. Here, I distinguish four ways to conceptualize PF: a psychodynamic developmental dimension, a descriptive summary of whatever all personality disorders or maladaptive traits have in common, a multidimensional model of traits, and a multidimensional model of adaptive capacities distinct from traits. I articulate the underlying assumptions and consequences for research and practice of each of these four approaches. I argue that conflating these assumptions has led to miscommunication about PF in the literature and describe how these models can be distinguished to provide more rigorous tests of the existence, nature, and utility of PF for personality theory and clinical assessment.