Schools
| School Name | Level | District |
|---|---|---|
| Oakland Elementary | District 10 | |
| Oakland High School | District 10 | |
| Oaklea Middle School | District 12 | |
| Oakridge Elementary | District 12 | |
| Oakridge High School | High School | District 12 |
| Oakridge Junior High School | District 12 | |
| Obsidian Middle School | District 5 | |
| Ocean Crest Elementary | District 7 | |
| Oceanlake Elementary | District 11 | |
| Ochoco Elementary | Elementary School | District 5 |
| Ockley Green | District 1 | |
| Ogden Middle School | District 13 | |
| Old Mill Center for Children & Families | District 11 | |
| Oliver Elementary School | Elementary School | District 2 |
| Ontario High School | District 9 | |
| Ontario Middle School | District 9 | |
| Open Meadow High | District 2 | |
| Open Meadow Middle School | District 2 | |
| Opportunity Center | District 12 | |
| Opportunity House Sheridan | District 3 |