Napa County, in California's North Coast Range, is well known for its plant diversity. However, until now no one has published a listing of bryophytes for Napa County. I present a catalogue of 158 moss species in 77 genera and 31 families collected and confirmed as occurring within Napa County. The catalogue summarizes 1701 collections (1550 by me). Collection dates encompass 1866 through 2018. I examined selected collections at CAS, UC, and other herbaria, and sent many of my collections to specialists for their identification. I did not collect 11 species reported previously by others. Eighty-six species are collected at only one or two locations. The catalogue includes a summary of the distribution of each species in Napa County and a citation of reference collections deposited in herbaria (CAS, ILL, and UC). In addition to the cited collections, I deposited most of my other Napa County materials at CAS and UC. The number of collections of each species, their number of locations where collection occurred, and whether specimens were collected by me or others is presented. A comparison of the increasing numbers of mosses collected in the Napa County over time with that of nearby areas and California is summarized.