The Library had its start when, in 1890, the Escondido Dramatic Club began to use its profits to purchase books and make them available at a local school "for the use of the pupils and the general public".

On the March 13, 1893 meeting of the association, the by-laws and constitution were adopted and a week later, the Library Board of Trustees were elected for a term of one year.

[5] In January 2013, the Escondido Technology Center (ETC) was re-opened in part of the original space of the East Valley Branch.

Located in the brick Mathes Center building next to the Main Library on 247 S. Kalmia Street, the Pioneer Room was established in 1992, with bequest from local historian Frances Beven Ryan (1901–1990).

The research room and archives is a part of the Escondido Public Library that provides the community non-circulating reference material.

In March 2016, the San Diego County Grand Jury issued a report after "questions [were] raised concerning the adequacy of the library to server the community."