In addition to reviewing representative studies of genetic and environmental factors imputed in the etiology of the personality disorders (PDs), a number of models for conceptualizing and conducting etiological research are considered. In particular, it is proposed that research should initially concede a tripartite model (with separate temperament, personality, and disorder components). Such a model would allow identification of etiological factors having specificity to one or more components, and ones that are nonspecific in having relevance to all components.