The Sonoma County Library Photograph Collection consists of photographic prints, film negatives, and born digital images documenting the Sonoma County and north Bay Area history. The collection is organized into four series: 1. Photographic Prints, 1843-2015, 2. Film Negatives, about 1930-2005, 3. Digital Photographs, 2000-2022; and 4. Digitized Photograph Optical Discs. The photographic print series includes over 33,000 photographic porints and reproductions, including cartes-de-visite, cabinet cards and ambrotypes; prints are organized by accession number. The film negative series consists of 32 boxes of negatives, containing approximately 22,000 frames; negatives are filed by the corresponding print accession number. The digital photograph series are born-digital images; these are stored online. The digitized photograph optical disc series are scans from the print series accessions numbers 1- stored on CD-ROM and DVD-ROM (all digitized materials are also stored online. The photographs document the social, agricultural, religious, educations, business and political activities of Sonoma County residents and visitors from the late 1880s through the 2010s. Most of the photographs are family photos taken by family members and document the everyday life of area residents.

Some images in all series have also been assigned to additional collections by photographer, donor or project, but are currently included and interfield with the general collection. These include prints and negatives in the Don Meacham Photography Collection, Sonoma County Library Aerial Photogaphry Collection, Sopnoma County Historical Society Photograph Collection, and others.