| School Name | Street Address | City | State |
| Oak Grove School |
220 West Lomita Ave.
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Ojai | CA |
| Oakwood Friends School |
22 Spackenkill Road
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Poughkeepsie | NY |
| Ojai Valley School |
723 El Paseo Road
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Ojai | CA |
| Oldfields School |
1500 Glencoe Road
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Glencoe | MD |
| Olney Friends School |
61830 Sandy Ridge Road
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Barnesville | OH |
| Oregon Episcopal School |
6300 S.W. Nicol Road
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Portland | OR |
| Oxford Academy |
1393 Boston Road
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Westbrook | CT |