Incorporated in 1898, the Society collects, preserves, and makes available materials of historical character and interest, and collaborates with other groups and individuals with similar aims.

[1] Its mission, as expressed in the first volume of its Oregon Historical Quarterly, was to "bring together in the most complete measure possible the data for the history of the commonwealth, and to stimulate the widest and highest use of them.

[3] Shortly after its formation, the Society opened its first office and museum in Portland City Hall and began the development of a regional research library and a collection of historical artifacts.

[8][9] Chet Orloff, who had left OHS in 1987 for the Ninth Judicial Circuit Historical Society in Pasadena, California, was considered by The Oregonian to be heir-apparent, but Bill Tramposch was brought in from Williamsburg, Virginia.

[15] George L. Vogt, a former president of the American Association for State and Local History was appointed as the eighth Executive Director of OHS in November 2006.

[27] From 1986 to 2001,[28] the Society used the former Meier & Frank Delivery Depot, in the Pearl District, to house its collection (except items on display at the museum at any given time) and for processing of new acquisitions.

[29] In 2000, after property values began rising due to redevelopment in the Pearl that started in the late 1990s, the Society sold that building, for $12.7 million.

[28] Noting that the four successive presidents after Harvey Scott were attorneys, historian E. Kimbark MacColl stated: young Portland lawyers at the turn of the [20th] century ... rose to civic prominence, ... became actively involved in the Oregon Historical Society, and ... were instrumental in fabricating an "Oregon Story" that was heavily laden with mythology, hero worship and pioneer idolization.