A vegetation inventory of Gouldsboro State Park carried out between August 2001 and February 2006 revealed the presence of five plant species listed by the Pennsylvania Natural Heritage Program. Gouldsboro Lake contains populations of Farwell's watermilfoil, and small beggar-ticks; bog sedge and Labrador-tea were found in a bog in the southern part of the park, and forked rush was located along wetland margins in the southern part of the park. Overall plant diversity in the park, 291 species, was comparable to that found previously in Tobyhanna State Park. Non-native species comprised 17.4% of the total species present. In all fifteen different plant community types were distinguished on the vegetation map. Northern hardwood forest was the most common upland vegetation type. Several wetland vegetation types were present in poorly drained swamps and bogs. Recommendations include 1) reducing deer density to allow impoverished understory, shrub, and herbaceous layers to recover; 2) controlling populations of the invasive plant common reed, to prevent its spread into high quality wetland habitat; and 3) monitoring PHNP-listed plants including aquatic species in Gouldsboro Lake once the dam is repaired.