| Onion Creek School District, WA (District) |
| Onondaga Central School District, NY (District) |
| Onondaga County, NY (ISD) |
| Onondaga-Cortland-Madison Boces, NY (ISD) |
| Onslow County, NC (ISD) |
| Onslow County Schools, NC (District) |
| Onsted Community Schools, MI (District) |
| Ontario County, NY (ISD) |
| Ontario Local School District, OH (District) |
| Ontario Sd 8C, OR (District) |
| Ontario-Montclair, CA (District) |
| Ontech Charter High School, NY (PSA) |
| Onteora Central School District, NY (District) |
| Ontonagon Area Schools, MI (District) |
| Oologah-Talala, OK (District) |
