Frogmore is an unincorporated community on St. Helena Island in Beaufort County, South Carolina, United States, along U.S. Route 21. Located halfway between Beaufort and Hunting Island State Park, the Frogmore area is primarily rural but is considered to be the commercial center of St. Helena Island. Frogmore is also the name of a plantation that has been listed on the National Register of Historic Places. The plantation is located off Seaside Road on Frogmore Manor Drive and is significant for its association with Laura Towne and Ellen Murray, the founders of Penn School.