The Metropolitan Water District of Southern California manages a library and archival repository documenting the activities of the organization and resources of interest to the greater history of the Los Angeles region. 

Mount Saint Mary's University was founded by the Sisters of St. Joseph of Carondelet in 1925 as the first Catholic women's college west of the Mississippi. It comprises two historic sites, the Chalon Campus high above Brentwood (1930), and the Doheny Campus, which occupies the former estate of Edward and Estelle Doheny, including the Doheny Mansion at 8 Chester Place (1899).

The Baseball Reliquary maintains a large collection of artifacts, artworks, photographs, and documents related to baseball history in Southern California and the United States.

The Special Collections holdings reflect the diverse communities of the Claremont Colleges and the local area and region. Among the collections especially pertinent to Los Angeles and Southern California are the following:

The Drucker Institute, in cooperation with the Honnold/Mudd Library at the Claremont Colleges, maintains a collection of records donated by Peter Drucker and others with whom he interacted. The archives’ purpose is to support research related to Drucker’s life and work. The collection includes articles written by or about Peter Drucker, images and magnetic media, boxed awards and ephemera, and…