245 described species, two undescribed species and four varieties of moss are documented on the Plumas National Forest, California representing approximately 35% of the California moss flora. Nineteen species are new records for the Sierra Nevada mountain range of California. The high rainfall on the western slope of the forest and associated habitat conditions allow for many disjunct coastal species. Four species, Pohlia flexuosa Harv. in Hook., Schistidium subjulaceum H.H. Blom, Scopelophila ligulata (Spruce) Spruce, and Sphagnum angustifolium (Russow) C. Jensen in K. R. Tolf, were found new to California during this study. Five species, Gemmabryum vinosum J.R. Spence & Kellman, Homalothecium californicum Hedenäs, Huttunen, Shevock & D.R. Norris, Orthotrichum confusum R. Medina, F. Lara & Garilleti, Ptychostomum pacificum J.R. Spence & Shevock, and Schistidium splendens T.T. McIntosh, H. H. Blom, Toren & Shevock were recently described, partially using material collected as part of this study.