AbstractFrom research on the organization of implicit personality theory, and on the fakability of psychometrically sophisticated scales a general argument about the conceptual overlap between implicit personality theory and ‘scientific’ theories of personality is developed. This is tested in the case of the common‐sense conception of extroversion—introversion, and that of Eysenck. The convergent validity of these two conceptions are found to be high enough to support the argument. The implications of the argument are discussed in relation to the correspondences between implicit personality theory and personality theory, and the functions of personality theory in psychology and implicit personality theory in everyd