The Friends of the Library is a volunteer organization dedicated to supporting the library by advocating for its essential role in enriching the cultural and educational lives of Park County citizens and by raising funds to provide for materials, programming, and facility improvements.

The Friends, in recent years, have raised funds to renovate the Carnegie Library ($200,000), expand the library building ($2,000,000), replace the boiler ($40,000), outfit and decorate the bookmobile ($25,000), renovate the children's areas ($65,000) to purchase new furniture ($22,000). The net proceeds from the annual used book sales go to purchase library materials. The Friends co-sponsor two summer interns for the library. Funds are also used to support the summer children's reading program. The Friends sponsor the Carnegie Readers book discussion group and a free concert showcasing an ensemble from the Bozeman Symphony. Funds provided by the Friends pay the subscriptions for the many periodicals available at the library and are used for technology upgrades and a myriad of other items not covered by the library budget funded by tax dollars.