| Options | 17 | alternative | other |
| OPTIONS EARLY GRADUATION H S | 61 | alternative | high |
| Options For Youth - Duarte Inc | 3,369 | regular | other |
| Options for Youth San Gabriel | 244 | regular | other |
| Options for Youth-Acton | 2,171 | regular | other |
| Options for Youth-San Bernardino | 1,168 | regular | other |
| Options for Youth-San Juan | 720 | regular | other |
| Options for Youth-Victor Valley Charter | 886 | regular | other |
| OPTIONS H S | 136 | alternative | high |
| Options High School | 176 | alternative | high |
| Options Indiana | 612 | regular | other |
| Options Noblesville | 183 | regular | other |
| Options Secondary | 69 | alternative | other |
| Options Westfield | 248 | regular | other |
| OQUENOCK ELEMENTARY SCHOOL | 418 | regular | other |
| Oquirrh Hills Middle | 1,261 | regular | other |
| Oquirrh School | 524 | regular | elementary |
| Oradell Public School | 809 | regular | other |
| ORALIA R RODRIGUEZ EL | 499 | regular | elementary |
| ORAN ELEMENTARY SCHOOL | 139 | regular | elementary |
| ORAN HIGH SCHOOL | 165 | regular | other |
| ORAN M ROBERTS EL | 340 | regular | other |
| Oran P Lawler Elementary School | 470 | regular | other |
| Orange Avenue School | 414 | regular | other |
| Orange Avenue School | 750 | regular | elementary |
| Orange Beach Elementary School | 600 | regular | other |
| Orange Beach MiddleHigh School | 662 | regular | other |
| ORANGE BROOK ELEMENTARY SCHOOL | 667 | regular | other |
| Orange Center Elementary | 261 | regular | elementary |
| ORANGE CENTER ELEMENTARY | 342 | regular | other |
| Orange Center School | 80 | regular | elementary |
| ORANGE CITY ELEMENTARY SCHOOL | 594 | regular | other |
| Orange City Elementary School | 672 | regular | elementary |
| Orange County Academy of Sciences and Arts | 249 | regular | elementary |
| Orange County Classical Academy | 740 | regular | other |
| Orange County Educational Arts Academy | 643 | regular | elementary |
| Orange County High | 1,477 | regular | high |
| ORANGE COUNTY PREPARATORY ACADEMY CHARTER | 286 | regular | elementary |
| Orange County Special Education | 331 | special-ed | other |
| Orange County Workforce Innovation High | 210 | regular | high |
| Orange Cove High | 635 | regular | high |
| Orange Early Childhood Center | 195 | regular | other |
| Orange Elementary | 746 | regular | elementary |
| Orange Elementary | 621 | regular | other |
| Orange Elementary School | 518 | regular | other |
| Orange Glen Elementary | 470 | regular | elementary |
| Orange Glen High | 1,788 | regular | high |
| Orange Grove Charter School | 1,170 | regular | other |
| ORANGE GROVE EL | 516 | regular | elementary |
| ORANGE GROVE EL | 386 | regular | elementary |