While it contains many thousands of unique original documents of historical significance, it is only a portion of the original Modenhauer Archive that was located in Spokane, Washington and founded and collected by musicologist Hans Moldenhauer.

Moldenhauer's very large collection of original manuscripts by Anton Webern, considered to be the most important holding, are now in the Paul-Sacher-Stiftung Library in Basel, Switzerland.

The collection spans musical periods from the Middle Ages through the 20th century, and includes original musical manuscripts by 57 of the foremost western composers, from Bach, Bartók, Beethoven and Brahms, via Mahler, Mendelssohn and Mozart, to Schubert, Schoenberg and Webern.

Since 1987, the Moldenhauer Archives have grown to many thousands of items that are now housed in nine institutions around the world: in the United States, at the Library of Congress, Harvard University, Northwestern University, Washington State University, and Whitworth College; in Basel, Switzerland, at the Paul Sacher Foundation; in Zürich, Switzerland, at the Zentralbibliothek; in Munich, Germany, at the Bayerische Staatsbibliothek; and in Vienna, Austria, at the Stadtarchiv und Oesterreichische Nationalbibliothek.

Hans Moldenhauer was born in 1906 in Germany, but emigrated to the United States in 1938 to escape fascism in his native country.