In this chapter I describe the introduction of a new concept, “personality,” into the language of psychology and psychopathology of the late nineteenth century. Personality was introduced in a clinical–pathological context but was transferred to a psychometric context by American psychologists. In medicine, in the middle part of the twentieth century, although several types of “psychopathic personalities” were described, most of psychopathology was considered personality related. “Personality disorders” came to be seen as treatment-resistant and conceptualized as lying in a borderline region between neurosis and psychosis. In the Diagnostic and statistical manual of mental disorders version III (DSM-III), personality disorders were more thoroughly segregated from the rest of psychopathology. After the publication of the DSM-IV (and the International classification of diseases version 10, ICD-10), psychological scientists began to assert themselves, reinvigorating the old the contrast between a clinical–pathological method and a psychometric, factor-analytic approach as a “categorical” versus “dimensional” debate. More recently, the aspiration to apply factor-analytic psychometrics to psychopathology in general has the potential to reverse the separation introduced in the DSM-III and re-nest psychopathology under personality.