The lexicostatistical method is frequently used to gain information about family trees of languages which are not accessible in study by more traditional methods. The first & major purpose of this work is to validate the lexicostatistical method by presenting the classification it yields for the Indoeuropean family, & comparing that classification with the traditional one. If the classification it yields had differed greatly from the generally accepted one, some would have found that reason enough to challenge the method. The differences, however, appear to be relatively small & subject to reasonable explanations. Consequently this classification can be regarded as a principal confirmation of the validity of the lexicostatistical method. Illustrations.