Titles: O
- Oaks Park Pentimento: Portland's Lost and Found Carousel Art
- On the Highest Hill
- On Interpretation: Sociology for Interpreters of Natural and Cultural History
- On the Ragged Edge of Medicine: Doctoring Among the Dispossessed
- On the Run: Finding the Trail Home
- One City’s Wilderness: Portland’s Forest Park
- The Only Woman in the Room: The Norma Paulus Story
- Oregon: There and Back in 1877
- Oregon Archaeology
- Oregon Coastal Access Guide: A Mile by Mile Guide to Scenic and Recreational Attractions
- Oregon Detour
- Oregon Fossils
- Oregon Geology
- Oregon Indians: Voices from Two Centuries
- Oregon Painters: Landscape to Modernism, 1859-1959