The DSM-III distinction between schizoid and avoidant personality disorders is examined. This distinction derives from Millon's bio-social learning theory and his interpretation of Kretschmer's personality types. Kretschmer's depiction of schizoid personality emphasizes the ratio between hyperaesthetic and anaesthetic tendencies. It is argued, therefore, that the division of this continuous distribution into two distinct personality disorders is historically inaccurate. Clinical case material is used to illustrate this misconception.