Freyd's list of introvert traits was applied as a rating scale to 900 students at the University of Minnesota. Of these a random sample was chosen and made the basis of this study. Although the study is merely preliminary and exploratory the results seem to justify the following statements: (1) Introverts and extroverts are not distinct types, but belong to a single mixed type of which introversion and extroversion are extremes; (2) the central tendency of the group shows an appreciable deviation toward extroversion, according to the scale used; (3) individuals tend to rate themselves as more introverted than their associates judge them to be; (4) there is greater agreement between self-ratings and associates' ratings than between the ratings of two associates; and (5) on the basis of statistical analysis, Freyd's list is justified as an instrument for distinguishing between introverts and extroverts. (PsycINFO Database Record (c) 2006 APA, all rights reserved)