The first historical society was formed in Decatur County about 1916 and revived in 1924. It ceased to exist in 1954. The present society was organized in 1959 as part of the Greensburg centennial observance.
The purpose of the society is:
- to discover, procure, and preserve documents, papers, books, articles, and things that may relate to the natural, civil, literary, and ecclesiastical history of the State of Indiana and to the County of Decatur in particular
- to establish and maintain collections in art and archaeology
- to establish a museum in order to exhibit and preserve objects of permanent interest in the history of the United States, the State of Indiana, and Decatur County
- to preserve objects of permanent interest in the arts and sciences
- to promote a general interest in the history of our county and the people thereof