Millon has proposed six fundamental dimensions of general personality functioning as providing the underlying structure of personality disorders. However, this widely-cited theoretical model has been the subject of few empirical studies. The purpose of the current study was to directly compare the validity of this model to the five-factor model with respect to their hypothesized relationships with personality disorder symptomatology. Participants were administered the predominant measures of general personality functioning for each theoretical model, along with an assessment of personality disorder symptomatology. The results found only weak support for the theoretical model of Millon. Limitations and suggestions for future research are discussed.