Before human intervention, the vegetation of Puerto Rico was mostly a tall mesophytic forest, but the advent of European settlement after 1500 brought profound changes. By the end of the nineteenth century, a very large part of Puerto Rico had been denuded. However, in recent times, a significant increase in forest cover - in part by the establishment of state forests - has improved the growth opportunities for ferns. This volume is a comprehensive overview of the ferns of Puerto Rico and also the Virgin Islands, as they exist today. Included in the treatment are keys, descriptions, black and white illustrations, and distribution information.