A descriptive floristic study of the vascular flora and plant communities was conducted at the John B. Stephenson Memorial Forest State Nature Preserve in Rockcastle County, Kentucky, during the growing seasons of 1997-98. This 51-hectare rugged natural tract of the Berea College Forest, formerly known as Anglin Falls Ravine, is the 36th Kentucky State Nature Preserve. The vascular flora consists of 98 families, 310 genera, and 538 species (56 of these non-native). Species are classified into Lycopodiophyta (4), Polypodiophyta (29), Pinophyta (5), and Magnoliophyta (500). The four largest families in species are the Asteraceae (79), Poaceae (46), Cyperaceae (35), and Fabaceae (20). Eleven plant communities are described from field survey and plant sampling work. Seven are forested, two are microhabitats within those seven communities, one is a wetland meadow, and one is a culturally disturbed community. The Preserve supports an excellent example of protected Mixed Mesophytic Forest in the Northern Cumberland Plateau of Kentucky.