The Cornerstone Genealogical Society is a non-profit unincorporated organization dedicated to preserving the genealogical history of Greene County, Pennsylvania. The society was formed in 1975 to assist individuals to learn more about their ancestors who, at one time or another, may have resided in or around Greene County.

The historical and genealogical significance of Greene County has long been recognized by persons interested in family history and the migration patterns of the early settlers of this nation.

Greene County is located in the southwest corner of the State of Pennsylvania. Once a part of Westmoreland County, it is bordered on the west and on the south by West Virginia. The Cornerstone Genealogical Society derives its name from the geographic significance of Greene County as comprising the southwest corner of the state.