A total of 83 taxa of Musci are enumerated from the prairies of Alberta, Saskatchewan, and Manitoba. These are composed of 36 soil-dwelling species, 21 that occur on rotting vegetation, 8 aquatics, 6 rupestral, and 3 corticolous. A large number of new provincial records are reported as well as the speciesMnium arizonicum, new to Canada. None of the species are endemic to the prairies and most attain greater abundance in neighboring wooded regions. The ecology of the region and early collections are discussed.