The Friends of the Folsom Library operate the book store in the Library Rotunda. Their shop, conveniently located by the Library's main entrance, is open Tuesday through Saturday 10 a.m. to 4 p.m. The Friends book store resells gently-used, donated books to raise money for the Library. They accept donations of hardcover, paperback, children's books, comics, DVDs, and CDs. They also sell cards that are handmade by volunteers.

The Friends of the Folsom Library is a volunteer-run, charitable organization whose sole purpose is the support the Folsom Public Library. The Friends generous donations fund library programs, services, and the purchase of new materials for the youth and adult collections. If you would like to support the library through the Friends, consider joining as an annual member, donating used books, or donating monetarily. More information at their website foflib.org.