The purpose of this series of studies was to investigate aspects of the validity of the Instrument Timbre Preference Test (ITPT) (Gordon, 1984). Subjects for different phases of the study were drawn from populations of undergraduate non-music majors, undergraduate and graduate music majors, and university music faculty (N=459). Criterion-related validity was examined as follows: a) subjects' identification of the seven synthe- sized timbres of the ITPT according to the instruments they represent; b) subjects' responses to a questionnaire pertaining to reasons underlying the choice of a beginning band instrument; and, c) mean comparisons of timbre preferences among subgroups of instrumentalists. Results supported the criterion-related validity of Timbres A, B, and E and the test re-test -reliability of Timbres A and G. Results did not support the criterion- related validity of Timbres C, D, and F, and the reliability of Timbres B, C, D, E, and F.