Intended as the first installment of a two-volume set (the second part remains unpublished), this English-language pteridoflora treats about 560 out of an estimated 1100 species in the floristically rich region of Costa Rica, Panama, and adjacent portion of Colombia. The volume comprises 20 families of ferns and lycopods, including such important groups as tree ferns, filmy ferns, and polypods. The treatments include keys, drawings of the taxa, extensive notes on nomenclature, synonymy, and typification, as well as brief statements of distribution and habitats.