The society is a statewide membership organization that provides leadership in public historical education. It collects, preserves, and interprets materials exemplifying the history of the state. The society's mission guides its acquisitions, collections management, exhibitions and publications. To serve the citizens of Washington, the geographic emphasis for the society is the entire state, but for contextual purposes, the history of the northern American West and north Pacific regions, broadly conceived, fall within the scope of the society's concerns. Chronologically, the full sweep of human history in Washington is the society's arena, from initial habitation by the native peoples to the modern era.