The need for conservation of bryophyte and lichen species and their habitats is being increasingly recognized in the United States and Canada. However, relatively few species in these groups have been formally identified as conservation priorities. Scientific staff of The Nature Conservancy (and now the Association for Biodiversity Information), working in cooperation with various bryologists and lichenologists and with state and provincial conservation botanists, began documenting bryophyte and lichen species of conservation concern in the mid-1980's. By early 2000, initial review had been completed for all North American liverworts and hornworts and most mosses, but only a few hundred lichen species. Data are being developed using the Conservancy/Heritage system of global conservation priority ranks (G1 - G5, with G1 for rarest or most vulnerable, and G5 for widespread, abundant, and secure). Our goal is to conduct initial screening of all species accepted in the pertinent ABLS checklists, determining an estimated rank for each. We can then give greater attention to those initially considered globally rare (G3 or rarer). Data sources include revisions and floras, articles in The Bryologist and other journals, consultation with experts, and information from interested conservation botanists, such as those at state Natural Heritage Programs, provincial Conservation Data Centers, and federal land-management agencies. Nominations of species that are rare, threatened, declining, or vulnerable from a range-wide (global) perspective, as well as confirmations that various other species (when considered range-wide) are indeed widespread, abundant, and secure, are both sought by the authors from interested specialists. Results of this work are being provided to federal conservation agencies and other partners, and will be distributed publicly through ABI's web site NatureServe.

Key words: Bryophytes, Conservation, Lichens