The history of the Memorial Branch Library began in 1923, seven years before the building opened. That year, the land on which the library now stands was purchased by the student body and alumni association of Los Angeles High School, and deeded to the City of Los Angeles in commemoration of twenty alumni who died in World War I. Six years later, the city gave the Los Angeles Public Library the right to establish a branch on the site.

The library formally opened on April 29, 1930. The architectural firm Austin and Ashley designed the building in a picturesque English Tudor style to harmonize with the high school building across Olympic Boulevard, which they also designed. The students of Los Angeles High School commissioned a stained glass window with the names of the twenty alumni and an inscription stating hope for “peace among nations.” The window, designed by the renowned Judson Art Studio, was inspired by those in the Parliament Building of London and was installed in the adult reading room.

On the memorial stained glass windows:
"The symbols and insignia are shown as decoration on the shields and in the top row of windows represent the various armed forces -- the Infantry, Field Artillery, Navy, Marine Corps, Engineers and Aviation.

In the second row of windows the tower of the old L.A. High School, the seal of the city of L.A., the coat of arms of the United States, the California state flag, the coat of arms of the L.A. High School, and the tower of the present L.A. High school building are represented.

The lower row of light (two center panels) have the memorial tablets giving the names of the alumni who died in the service. The shields on either side carry the emblem of ""Sacrifice,"" pictured by the legend of the Pelican in Piety, and on either end is an heraldic arrangement of the poem ""In Flanders Field.""

Across the base of the window is the inscrIption ""Dedicated to the Alumni of the Los Angeles High School who died in the World War. 1914—1918. May the sacrifice of these lives contribute to the establishment of peace among nations.”