ABSTRACT
The Library of Congress' Thesaurus for Graphic Materials (TGM) is one of the major thesauri used for indexing visual materials. Developed by the Library's Prints and Photographs Division (P&P) in the 1980s, the thesaurus has become an essential tool for numerous libraries, archives, and historical societies that catalog images, in the United States and abroad. This article will trace the history, development, and current use of TGM in P&P and other institutions, and take a look at its future, addressing subject indexing guidelines and principles along the way.
