The lichens of Prince Edward Island (PEI) are well known to have been inadequately sampled and not well understood. In this study, 19 biologically diverse forest remnants and other potentially rich localities were explored for their lichen vegetation, and 118 new county records and 71 species new for the province were discovered. Together with previously studied sites, 38 localities in total have now been surveyed. A new checklist based on these surveys was prepared for all the lichens of the island. In addition, conservation status (S-ranks) is proposed for 153 species of the 326 species in 118 genera now known for the province. Four species received a rank of S1 (critically imperiled): Anaptychia crinalis, Megaspora verrucosa, Pannaria lurida, and Sclerophora amabilis; and six species received a rank of S2 (imperiled): Acrocordia cavata, Bryoria salazinica, Heterodermia speciosa, Menegazzia terebrata, Pannaria rubiginosa, and Ramalina thrausta. The importance of baseline data for future conservation planning, pollution monitoring, and climate change studies is emphasized.