Twenty species of the crustose lichen genus Ochrolechia are represented in the flora of North America north of Mexico. The species are described and illustrated and their ranges given by the citation of specimens and by maps. Two species, O. farinacea from Washington and Oregon and O. sorediosa from Alberta, are described as new and one new combination, O. pterulina (Nyl.) Howard (= Lecanora tartarea var. pterulina), is made. Published in The Bryologist, volume 73, issue 1, on pages 93 - 130, in 2007.