Functions as a regional historical society, operating multiple historical sites in Northeastern Ohio. Sites include: Cleveland History Center, Hale Farm and Village, Macedonia Preservation Facility, Research Library, and Shandy Hall, Chisholm Halle Costume Wing, and the Crawford Auto Aviation Collection .

Operates the Wolcott House Museum Complex which includes the Wolcott House, Federal Style House, Gilbert-Flanigan House, Saltbox Style House, Log Cabin, Railroad Depot, a museum store in a Greek Revival House, and a Country Church and 1850s one-room county schoolhouse. The Society publishes the Journal of Northwest Ohio and books on Maumee Valley's history and maintains a 4,000-volume historical library housed at the Toledo-Lucas County Public Library's local history department.

Offers materials and resources for genealogists and others. Provides exhibits of Ohio's history. Includes facts, data, and evidence from letters, reports, notes, memos, photographs, and other primary sources. Preserves graphic information regarding Ohio's history.

Promotes the study and appreciation of the history of Geauga County. Preserves, acquires, maintains, and restores historically significant sites, buildings, and items for the enjoyment and education of current and future generations. Operates Century Village which is a fully restored Western Reserve village available for visits and tours.

Provides educational programs for youth and adults through a Museum Community Center and Gift Shop. Memberships are available.

Provides a collection of historical documents and artifacts which document the history of the Cleveland Police Dept. from 1866-present. Among the records available in the archives are annual reports, directories, manuals, police blotters, scrapbooks and over 12,000 photographs. Customized group tours may be arranged.

Works to preserve the history of Columbus by collecting and archiving materials relevant to the history of the city. These materials, along with others from local collectors and organizations, are on display at the museum.