The Library of Congress [LC] Classification system is a system of letters and numbers assigned to a book based upon its topic. Books in university libraries are shelved according to the LC call number. This results in books on similar topics being shelved near each other on the shelves.
LC is used by Indiana State University Libraries for assigning call numbers to the bulk of its collections. The following chart provides a very simplified breakdown of the LC system and some of the subject areas represented by specific letters and letter combinations. Important LC Numbers of Interest to Music Researchers include:
| M | Music |
| M5-1490 | Instrumental Music |
| M1495-5000 | Vocal Music |
| ML | Literature on Music |
| ML112.8-158.8 | Music Bibliography |
| ML159-3775 | Music History and Criticism |
| ML3800-3923 | Philosophy and Physics of Music |
| MT | Musical Instruction and Study |
| MT955-956 | Musical Theater |
